One population of the grey mullet mugil cephalus inhabits the waters around the Taiwan Strait and in the spawning season migrates to the coasts of southern Taiwan. The grey mullet is long-lived and produces a great number of small, nonbuoyant eggs. The female grows larger in size and shows high GSIs than the male. Lee's phenomenon is marked in the grey mullet. These characteristics of grey mullet correspond well to its relatively stable pattern of fluctuation in numbers. None of the fish species examined by one of the authors, Kawasaki, shows such characteristics, which is interesting from the viewpoint of evolutionary ecology.

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In order to elucidate the food availability for fish larvae such as walleye pollock, Theragra chalcogramma, flathead flounder, Hippoglossoides dubius, abundantly inhabiting the surface layer in winter, copepod nauplii were collected at a depth of 15m from January to March 1991 in Funka Bay and surrounding vicinity. Body width of copepod nauplii ranged from 40 to 322 μm. Many nauplii (64.8%) passed through a 100 μm mesh sieve, especially for copepod nauplii smaller than 100 μm (89.6%). From January to March, Oithona nauplii were abundant (2.14-13.52 indiv./l), accounting for 53.6-91.0% of total copepod nauplii except at the mouth of the bay in March (25.9%). The width of Oithona nauplii ranged from 40 to 178 μm and 75.2% were smaller than 100 pm. Most nauplii (<100 μm, 90.4%) passed through a 100 μm mesh sieve. Numbers of Pseudocalanus & Metridia nauplii were small in January (0.66-0.97 indiv./l), then increased in March to a maximum density of 4.57 indiv./l at the mouth of the bay. The width of Pseudocalanus & Metridia nauplii ranged from 79 to 195 μm and 90.2% were larger than 100 μm. Most of them (>100 μm, 82.8%) were obtained with a 100 μm mesh sieve.

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Larvae of walleye pollock Theragra chalcogramma were collected by vertical haulsfrom the sea bottom to the surface with a NORPAC net from January to March 1991 in Funka Bay and surrounding vicinity in Hokkaido. Larvae were abundant in January and decreased in February and March. To clarify the food availability of walleye pollock larvae at the initial feeding stage, the size of food for larvae smaller than 7mm in total length (TL) were measured. The total length of larvae collected in January ranged from 4.2 to 6.5mm. Most of 4.2-5.1mm TL larvae had empty stomachs. Food organisms were found from 7 larvae (4.8-6.5mm TL). Among them, copepod nauplii were dominated (60.5%), followed by invertebrate eggs (25.6%) and copepodids (13.9%). The body width of Oithona nauplii in the stomachs ranged from 84 to 121 μm and Paracalanus nauplius was 103 μm. Larvae of 4.0 to 13.2mm TL were collected in February. Six larvae (<7.0mm TL) fed on copepod nauplii (67.6%), invertebrate eggs (20.6%), copepodids (8.8%), and diatom Coscinodiscus sp. (3.0%). Copepod nauplii in the stomachs were larger than 95 μm in width. In March, food organisms taken by 5 larvae (<7mm TL) consisted of copepod nauplii (54.5%), invertebrate eggs (36.4%), and copepodids (9.1%). The width of copepod nauplii in the stomachs ranged from 156 to 176 μm. From these observations, it is considered that the primary food items of larval walleye pollock at the initial feeding stage are largesized copepod nauplii (>84 μm) in this area.

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Temperature, salinity, oxygen saturation, and occurrence of the greasyback shrimp Metapenaeus ensis were measured at the mouth of the Yodo River in September 1992 and 1993. Indoor experiments were also conducted on the juvenile greasyback shrimp, juvenile kuruma prawn Penaeus (Marsupenaeus) japonicus, young swimming crab Portunus (Portunus) trituberculatus, and the common brackish goby Acanthogobius flavimanus to examine their tolerance to low saturations of oxygen. The juvenile greasyback shrimp's habitat is at the bottom of the estuary where oxygen saturations decreased to 12-55%. Indoor experiments revealed that the mortality rate of the juvenile greasyback shrimp was only 25% when exposed to an oxygen saturation of 7-12% at 25° for 24 h and thatthis shrimp has a high tolerance to hypoxic conditions compared with the other three species. These findings suggest that, in spite of low oxygen saturations, the mouth of the Yodo River still plays an important role as a growing ground for the greasyback shrimp depending on the tolerance to hypoxic conditions.

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The relationships between the dominant phytoplankton and the factors of water quality were investigated at 28 stations in inland waters.
In large and deep lakes and dams between mountains, total nitrogen (TN), total phosphorus (TP), and TNxTP were low while TN:TP and dissolved inorganic nitrogen (DIN): dissolvedinorganic phosphorus (DIP) ratios were high. However, in small and shallow ponds the former water quality factors were high while the latter factors were low.
Uroglena americana, Fragilaria crotonensis, and Asterionella formosa occurred dominantly in waters with low water temperature (WT), TN×TP, DIP, and TN:DIN ratios and withhigh DIN, TN:TP, DIN:DIP, and TP:DIP ratios. On the other hand, the blue-green algae Microcystis aeruginosa, Microcystis wesenbergii, and Lyngbya contorta occurred in waters with high WT, TN×TP, TN:DIN, and TP:DIP ratios and with low TN:TP and DIN:DIP ratios.
These results suggest that DIN:DIP, TN:DIN, and TP:DIP ratios were closely related with the other factors of water quality, and these factors also restricted the waters where the specific phytoplankton occurred dominantly.

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A method is presented to estimate relative recruitment from catch-at-age data alone by applying fuzzy control theory. An important feature of this approach is that the natural mortality coefficient is not needed. Simulation tests were conducted to determine the performance of this approach including comparison with a conventional method. The simulations showed that the assumed trend of recruitment was well reproduced. The fuzzy method possessed a higher robustness to noise in the catch-at-age data than the conventional method. This approach is useful for the analysis of catch-at-age data.

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The nitrogen budget of the rotifer, Brachionus plicatilis, fed on algae (Nannochloropsis oculate) was examined using a ¹⁵N tracer technique. It was found that this technique could be used to measure the nitrogen budget of zooplankton using the difference in the turnover time between egestion and excretion. When food was unlimited, the assimilation efficiency, the gross growth efficiency (K₁), and the net growth efficiency (K₂) were 22.8, 17.4 and 77.5% respectively. Therefore, approximately 80% of the ingested nitrogen was egested into the culture medium and about 80% of the assimilated nitrogen was utilized for reproduction. The turnover time of egestion and excretion were about 20min and 2.5h, respectively. The obtained short turnover time for excretion is consistent with the hypothesis that assimilated nitrogen is used immediately and primarily for reproduction and the excess is stored in body tissue when food is abundant.

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Changes in morphological characteristics and thallus fragmentation patterns of anew member of Japanese Gracilaria, G. lemaneiformis, were investigated. The Gracilaria species occurs in abundant quantities all year round on the coast of Uranouchi Inlet in Tosa Bay, southern Japan. This Gracilaria species occurs mainly in the form of fragmented thalli. The thalli were categorized into two types: fragments possessing a holdfast (A) and fragments without a holdfast (B). The maximum length attained by A-type thalli was 123±36cm in July, while the maximum length of B-type thalli (121±23 cm) was obtained in September. The highest occurrence of A-type thalli (25.41%) was in January. However, the B-type thalli occurred in greater proportions than the A-type thalli throughout the sampling period. Seasonal changes by fragmentation, mostly without holdfast, and free floating forms with no reproductive organs, are specific characteristics of this Gracilaria species in Japan that have not been found in other species of Gracilaria.

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The diets and prey widths of Pacific cod (Gadus macrocephalus) larvae and juveniles were examined in Mutsu Bay. In early March, 11 yolk-sac larvae were caught in midwater ofthe bay mouth. Five of 11 larvae captured had not opened their mouths, and the remaining six had notfed. Post-larvae ≤ 7mm in total length (TL) fed on copepod nauplii, particularly Pseudocalanus nauplii. Prey items of post-larvae >7mm TL were chiefly crustacean eggs, and Pseudocalanus spp. copepodites and adults. From April to June, the main food organisms of cod juveniles were calanoid copepods, and changed from Pseudocalanus spp. to Calanus pacificus, Acartia clausi, and Centropages abdominalis. In addition, cod juveniles opportunistically fed on large-sized food organisms, namely, reptant megalopae, planktonic gastropods, and natant zoeae. In July, cod juveniles mainly fed on benthic prey items, such as gammarid amphipods and fish. It seems probable that these large-sized food organisms play an important role as alternative prey for cod juveniles when they change their mainfood from calanoid copepods to benthic prey items.

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Semen of amago salmon Oncorhynchus masou ishikawae was diluted 6 times with extender solution (90% 300mM glucose+10% DMSO) and frozen on dry ice (the dry ice method) or on a stainless steel case floating on constant-temperature ethyl alcohol (the alcohol method). Pellets of various volumes (50-200 μl) that were frozen on dry ice invariably showed a high percent of fertility in spite of the difference in their freezing rates (FR; 50.3 to 29.9°C/min). The fertilityof pellets frozen by the alcohol method and exposed to -30, -50, -70, or -90°C before immersion in liquid nitrogen depended on the alcohol temperature. The highest fertility (87.5%) of 100 μl pellets wasobtained with samples exposed to-70°C (FR=92.6°C/min). Pellets frozen by the alcohol method at-30°C (FR=30.6°C/min) or-90°C (FR=125.6°C/min) showed low fertility rates (58.2% and20.4%, respectively). Two hundred μl pellets frozen by the alcohol method showed a similar percent of fertility to the 100 μl pellets of the same temperature, although their freezing rates were lower. These phemomena were also found in masu salmon O. masou masou spermatozoa. The present results indicate that for spermatozoa of both species, freezing rates in the range of 29.9 to 92.6°/min have little influence on the post-thaw fertility. The most critical factor for obtaining the highest percent of fertility in pellet methods is the temperature reached before immersion in liquid nitrogen, with approximately -70°C being the most suitable temperature for amago and masu salmon spermatozoa.

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In this paper we use regression analysis to forecast the abundance of mature ocellate puffer Takifugu rubripes recruits migrating into a spawning area in the Inland Sea of Japan. Firstly, we describe the age-structure of ocellate puffer and characteristics of landings byhandline and longline fisheries in the Iyo-nada and Bungo Strait areas. In these areas the ocellate pufferare mainly caught at O-or 1-year-old. Fluctuations in landings in these areas are largely attributable to the year-class strength and this is further seen in the landings around the spawning area of mature fish. Next, the yearly fluctuations of the largely immature ocellate puffer landings in the Iyo-nada and Bungo Strait areas were compared to those of landings of mature fish around the spawning area. The correlation coefficient peaked at 0.941 (P<0.001) for a time difference of 2 years between annual landings in the two areas from 1976 to 1993. As a result, it is interpreted that the variations of landings due to year-class strength in the Iyonada and Bungo Strait area are directly correlated to fluctuations in landings around the spawning area after 2 years. A predictive linear regression model described a regression equation of Y=0.420 (±0.0249 S. D.) X with Y-intercept of 0±26.47 S. D., where X and Y indicate landings in the Iyo-nada and Bungo Strait areas 2 years ago and landings in the setnet fishery around thespawning area, respectively. These findings strongly support the hypothesis that the same stock of ocellate puffer are found in both areas.

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Activin, a member of the transforming growth factor-β superfamily, has recentlybeen isolated from eel testicular cDNA library. Using an in vitro testicular organ culture system, we investigated the effect of human recombinant activin A and B in eel spermatogenesis. Addition of human recombinant activin A and B (10 ng and 100 ng/ml) to the culture medium induced proliferation of spermatogonia within 15 days in the same manner as addition of 11-ketotestosterone (10 ng/ml) for positive control. In cultured testes without activins, however, the proliferation of spermatogoniawas not observed. Although it is necessary to investigate the eel's own activin A and B protein, these results suggest the possibility that activin induces initiation of spermatogenesis in Japanese eel.

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The contribution of SS bonds to the elasticity of suwari gel from various actomyosins was investigated, in which the coexisting transglutaminase was inactivated. The actomyosins, whose SH groups were blocked (SH-blocked AM) and unblocked (SH-unblocked AM), were prepared, respectively, by shaking the starting actomyosins with and without N-ethylmaleimide in 8M urea. After removal of urea by dialysis, they were measured for transglutaminase activity, total SH content, and suwari gel forming ability. The transglutaminase activity of both the actomyosins became zero by the above treatment with urea. The suwari gel prepared by setting SH-unblocked AM paste at 40°C for 1 h was considerably higher in the breaking force than the gel from the paste of the SH-blocked one. By setting the AM paste, total SH content was somewhat decreased in the former, but scarcely changed in the latter.

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We examined the behavioral avoidance to pesticides using a Y-maze flow-through system. Carp showed avoidance responses to emulsions of benthiocarb, isoprothiolane, and fenitrothion at concentrations higher than 1.7, 6.7 and 490 μg/l, respectively. These avoidance thresholds were 3 log units, 3 log units and 1 log unit lower than each 48 hr LC₅₀ for the pesticides, respectively. Fenitrothion was the most ineffective to the avoidance among these three pesticides. The anionic surfactant sodium lauryl sulfate (SLS) was the most effective repellent among tested compounds in carp, and the threshold was 10-2 μg/l. The addition of 1% SLS to the concentration series of fenitrothion decreased the avoidance threshold. The threshold for the mixture of fenitrothion and SLS was 1 μg/l.

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Membrane fractions were prepared from tilapia Oreochromis niloticus liver using differential centrifugation. Lipid peroxidation in the membrane fractions was induced by incubation of equimolar solutions of ferrous sulfate and ascorbic acid (FeAs) which generate hydroxyl anions. The degree of lipid peroxidation was measured using the thiobarbituric acid method, and the potency of antioxidants was evaluated according to inhibition of the lipid peroxidation induced by FeAs.
The antioxidative activity of conventional antioxidants, such as butylated hydroxyanisole (BHA), α-tocopherol, and β-carotene, were assayed using the fish liver membrane fractions. BHA showed stronger antioxidative activity than a-tocopherol, although the antioxidative activity of β-carotene could not be observed because of its insolubility. Moreover, it was suggested that the fish liver membrane fractions were 11 to 12 times as sensitive as those of human and rat livers in detecting the antioxidative activity of α-tocopherol. Therefore, tilapia liver may effectively be used for screening antioxidants owing to its greater sensitivity.

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Agars of Gracilaria lemaneiformis, a new member of Gracilaria in Japan, were extracted by the alkali treatment method with various concentrations of NaOH (1, 3, 5, 7, 9%) at 80°C. The treated samples were incubated for 1, 2, and 3 hours. Agar gel strength, gel deformation, and apparent Young's modulus were measured, and showed excellent gel characteristics. The highest gel strength of 1706.8±164.0g/cm² was obtained from 1% agar of 3% NaOH, 3h treatment, with gel deformation of 9.9±0.9mm, and apparent Young's modulus of 171.7±1.1g/mm, compared with the other treatments in this study. Agar solutions of this seaweed could form a firm gel at the very low concentration of 0.5% agar. Sulfate and 3, 6-anhydro-L-galactose contents reached the highest value of 4.4% from non-alkali treated agar, and 48.1% from 3% NaOH, 3h treated agar, respectively. The methoxyl contents attained the highest value (1%) in non-alkali treated agar and 1% NaOH, 1h treated agar. The agar of G. lemaneiformis showed an essentially higher gel strength compared with the Japanese commercial grade agars.

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Endurability in 16°C air was investigated with the goldfish Carassius auratus acclimated at 26°C. The specimens were sampled after 0, 1, 3, 5, and 7h in air, and subjected to the following measurements. 1) Blood pH, PCO₂, and PO₂ were individually examined with a pH/blood gasanalyser. 2) Lactic acid and ethanol contents in the lateral muscles were colorimetrically measured by the enzymatic UV-method. Over time, blood pH decreased in contrast to the Pco₂ increase. Po₂ showed a concave pattern. Lactic acid decreased first, then increased convexly. Ethanol was first detectedat 1h, and the value gradually increased to a maximum of 0.41±0.116g per kg of tissue at 7h.

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Changes in the gel forming ability of microbial transglutaminase containing surimi made from 7 species of fish were studied during 12 months of their frozen storage. Surimi samples were made from walleye pollock, white croaker, bigeye, lizard fish, largehead hairtail, hachibiki and sardine, and about 0.03% MTGase was added. Considering the practical processing surimi, all surimi samples used were prepared in commercial surimi plants, and commercial size surimi samples in commercial packages were stored at-30°C in the refrigerater warehouse. The changes in gel forming ability of surimi were monitored by measuring the punch force and punch deformation of prepared kamaboko gel. The gel forming ability of surimi gradually decreased during frozen storage for 12 months and the decreases differed from each other, however, the addition of MTGase did not effect the decrease profile. Therefore, MTGase powder can be added to surimi at the time of production without affectingsurimi quality.

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The temperature dependence of the extension stress of myosin gel was examined asthe simplestmodel of kamaboko in order to elucidate the mechanism of the elasticity of kamaboko, one of the tradi-tional processed fishery foods in Japan. Myosin was extracted from greenling Hexagrammos otakii, and concentrated to 85mg protein/g gel. The myosin was ground with 0.6M KCl and gelled by heating at 80°C for 20min. The results were analyzed according to the equation derived from thermodynamics. The extension stress decreased with rise in temperature in the 10-80°C range, and accordingly the entropy along with the inner energy were found to increase with extension under a constant temperature. Based on these results, a model structure of the myosin gel was presented. According to the model, the force which is responsible for returning the myosin gel to its original state isa strong aggregation force, or the inner energy. As a result, the elasticity of the myosin gel was concludedto be energy elasticity.

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The uptake mechanisms of 3, 5, 3'-triiodothyronine (T₃) by isolated masu salmon hepatocytes were investigated. [¹²⁵I]T₃ uptake into the hepatocytes and its binding to nuclei were stereospecifically inhibited by unlabeled T₃. The uptake and binding affinity of T3 was 2-3 and 10 times higher than those of thyroxine (T₄), respectively. Isolated nuclei of masu salmon hepatocytes were seen to have one class of high affinity T₄ binding sites (dissociation constant, 5.73±0.29 nM; maximum binding capacity, 43.7±5.1 pmol per 5×10⁶ nuclei). Furthermore, it was seen that the uptake andbinding mechanisms were highly temperature dependent, showing maximum uptake at 15°Cand binding at 25°C. T₃ binding to the nuclei was 1/10 of T₃ taken up by the hepatocytes. Incorporated thyroxine was deiodinated to T₃ in the hepatocytes, and maximum T₃ concentrations were observed at 3 h incubation. The small amounts of 3, 3', 5'-T₃ were also observed in the hepatocytes, but metabolized rapidly. Our results suggest that the uptake mechanisms of thyroid hormone by masu salmon hepatocytes are similar to those demonstrated in mammals.

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The response of sexually regressed red sea bream Pagrus major to LHRH-a (des Gly¹⁰-[D-Ala⁶] LHRH ethylamide) was investigated during the non-spawning season, from November to December. Fifty-five fish were divided into five groups and the following treatments were accomplished: initial and final controls (not treated), LHRH-a 200 μg cholesterol pellet (group CP 200), LHRH-a 1 μg/day osmotic pump (group OP 1), and LHRH-a 5 μg/day osmotic pump (group OP 5). In all females in the three experimental groups, gonadal maturation and spawning were induced 12 to 14 days after implantation. The cumulative amounts of LHRH-a released from each mold during the period from pellet or pump implantation were about 11 μg (CP 200), 14 μg (OP 1), and 60 μg (OP 5), respectively. These results suggest that all treatments of LHRH-a were found to be equipotent in inducing red sea bream females to mature and spawn. It seems that the amounts of sustaining release of LHRH-a from LHRH-a 200 μg cholesterol pellet are enough to induce ovarian maturation, and a higher dosage of LHRH-a is not necessary. On the contrary, every treatment of LHRH-a showed insufficient effects on testicular maturation, and the possible cause was discussed. The results of the present study may be used as a basis for producing eggs and fingerlings all year round.

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The change in molecular weight in the native form of lipovitellin during in vitro oocyte maturation was examined by gel chromatography in Japanese flounder, Paralichthys olivaceus, a marine teleost which lays pelagic eggs. The major protein peak at 400 kDa in the gel chromatogram of post-vitellogenic oocyte homogenate disappeared, and a new 140 kDa peak was observed in ovulated eggs. Both 400 kDa and 140 kDa yolk proteins were immuno-reactable to the specific antiserum against female specific-serum protein, suggesting that the 400 kDa yolk protein was lipovitellin of this species and the 140 kDa one was a proteolytic derivative from the 400 kDa lipovitellin. The timecourse analysis of the proteolysis of the lipovitellin during in vitro maturation demonstrated that thelipovitellin of 400 kDa was cleaved into 140 kDa during the later half of oocyte maturation. In combination with the result of SDS-PAGE analysis, this seems to be caused by the proteolytic cut-off of the 108 kDa peptide which constructs 400 kDa lipovitellin.

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The mineralization Kinetics of low molecular fatty acids and glucose were investigated in the anoxic sediment of Uranouchi Inlet, Japan. The Vmax values of mineralization of acetate, propionate, lactate, and glucose were 0.30-2.68 nmol/g/h, 0.45-1.57 nmol/g/h, 1.34-3.68 nmol/g/h, and 0.47-1.86 nmol/g/h, respectively. Those of formate mineralization were highest in allsubstrates tested, 90.8-637 nmol/g/h: 3 orders of magnitude higher than the other compounds. Turnover time varied according to substrate and temperature, ranging from 1.5-4.2h for formate to up to 70h for acetate without molybdate. The highest V_max values and shortest turnover time of fatty acids mineralization were recorded in summer sediment samples. Thus, the anaerobic mineralization potential and turnover of fatty acids in the terminal steps of decomposition of organic matter were higher in summer than winter, and were mainly affected by the temperature of the sediment. Furthermore, sulfate-reducing bacteria accounted for a significant part of the mineralization potential and turnover.

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The oxygen consumption of carp of 0.0021-3.5 g (1 to 79 days old after hatching) was determined at 25°C by three different methods. Oxygen consumption in vivo of intact fish (M_{in vivo}) was determined by the semiclosed method and the constant flow method. Oxygen consumption in vitro of minced whole body (M_{in vitro}) was determined by manometry.
The relationship between oxygen consumption of an individual fish (M in μl O₂•min^-1) and body mass (W in g) was expressed by the equation M=aW^b. Mass exponent “b” was 0.831, and was identical for the three methods. The light condition had an effect on oxygen consumption in the semi-closed method, but not in the constant flow method. The value of “a” was 5.71 in the semi-closed method in the light, 4.56 both in the semi-closed method in the dark and in the constant flow method in the three light conditions, and 2.70 in the manometry method. The difference in the value of “a” among the different methods of respirometry is thought to be due to the difference of activity of fish.

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A simple solid-phase microtiter plate enzyme-linked immunosorbent assay (ELISA) for 17 α, 20 β, 21-trihydroxy-4-pregnen-3-one (20 β-S), a teleost maturation inducing steroid, was developed using 20 β-S-3-CMO-seradish peroxidase as the label, and a homologous antiserum raised in rabbits. Second antibody coated to the plate was used to capture the antiserum with labeled or unlabeled 20 β-S. Within three hours, a steep standard curve covering 1.5-192 pg/well was obtained. The sensitivity and precision of this ELISA was almost the same as those of ordinary steroid adioimmunoassays. This non-isotopic assay system also allows prompt measurement of 20 β-S in catfish plasma with good specificity.

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This study was undertaken to investigate the effect of varying myosin ratios on covalent cross-linking of a mixture of two different myosins or actomyosins by transglutaminase from carp muscle. The progress of cross-linking of myosin heavy chains (MHC) of carp, rainbow trout, and atka mackerel was significantly different; carp MHC formed mainly dimer at a rate of 8 μM•h^-1•unit^-1, but rainbow trout and atka mackerel MHC formed dimer and large polymers (n_??_3) at approximately the same rate of 55 μM•h^-l•unit^-1. The cross-linking rate of MHC in mixed myosins of carp and rainbow trout increased with increasing ratio of rainbow trout to carp. On the other hand, in the case of a mixture of rainbow trout and atka mackerel, the MHC in mixed actomyosins at any ratio were cross-linked to form large polymers at the same rate, suggesting the formation of co-polymers with each other.

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The effect of ascorbate was examined on the carnitine and lipid metabolism of fish. Young rainbow trout were fed on a single type of moist pellet supplemented with L-ascorbyl-2-monophosphate (AsP) or L-ascorbic acid (AsA) for 60 days and then starved for 60 days. Before and after starvation, As A and carnitine concentrations and lipid content in tissues were determined. Before starvation, long-chain acylcarnitine concentration in the liver was significantly reduced in the ascorbate-free group compared with the AsP-and AsA-supplemented groups. Lipid contents in AsP-and AsA-supplemented groups decreased significantly during starvation but not in the ascorbate-free group: it is considered that the fish whose AsA level was reduced could not consume lipid efficiently as an energy source during starvation. The results strongly suggested the participation of ascorbate in the carnitine and lipid metabolism in fish. AsP as well as AsA could prevent abnormal metabolism of carnitine and lipid, such as reduced long-chain acylcarnitine level and depression of lipid utilization during starvation, by raising the AsA level in the fish body.

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The effects of dietary energy sources on protein utilization by Colossoma macropomum fingerlings were studied. The fish were fed to satiation seven experimental isocaloric semi-purified casein diets with increasing dietary protein levels (from 0 to 48%). The energy content was adjusted with carbohydrates in four diets (11, 20, 31 and 48% protein) and with lipids in two diets (28 and 36% protein).
Daily feed consumption decreased and percent gain and feed efficiency increased with an increase in dietary protein. Dietary protein requirement was found to be more than 31% when carbohydrates were used as the energy source. Protein efficiency ratio and net protein utilization were inversely proportional to the dietary protein content and no negative effect of carbohydrates on protein utilization was observed. In terms of feed efficiency and protein efficiency ratio, the lipid and carbohydrate groups responded in a similar way to the dietary protein levels. Carbohydrates seemed to be effective as a dietary energy source for this species. The whole body lipid content was inversely proportional to the dietary protein level and was higher in fish fed the lipid diets than in those fed the carbohydrate diets.

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In order to investigate the effect of acclimation temperature on body composition, hepatopancreatic enzyme activities, and fatty acid synthesis in carp Cyprinus carpio, the fish were reared at the same feeding rate on a commercial diet at high (27°C) or low (17°C) water temperature. The contents of body fat and hepatopancreatic glycogen together with apparent fat retention were higher in the coldacclimated fish than in the warm-acclimated fish. Most of hepatopancreatic enzyme activities were high in the cold-acclimated fish, suggesting thermal compensation for low acclimationtemperature in the poikilothermic animal. The activities of lipogenic enzymes such as glucose-6-phosphate dehydrogenase and NADP-malate dehydrogenase, the level of serum triglyceride, and the rate of fatty acid synthesis from ¹⁴C-glucose and-alanine were also higher in the cold-acclimated fish than in the warm-acclimated fish. The results indicate that the fatty acid synthesis from glucose and amino acid in the hepatopancreas of carp is activated during cold acclimation, resulting in the accumulation of body fat.

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The inorganic constituents of fish bone ash were examined by both X-ray diffraction analysis and elemental analysis. Fifteen species of fish were selected from Teleostomi and Elasmobranchi. Cattle and swine as Eutheria and fowl as Neornithes were also investigated to compare with the Teleostomi and Elasmobranchii. All ashed bone samples were classified in to three groups composed mainly of either hydroxyapatite (HAP), β type Ca₃(PO₄)₂ (TCP), or their mixture; HAP type, TCP type, and HAP-TCP type. Sample species of the HAP type were sea bream, horse mackerel, carp, shark, cattle, swine, and fowl. The TCP type species was Japanese anchovy. HAP-TCP types were sardine, mackerel, tilefish, croaker, triggerfish, lizard fish, Spanish mackerel, flying fish, conger eel, and flat fish. Molar ratios of Ca with or without either Mg or Na to P for the examined bone ashes coincided with the theoretical values of HAP and TCP.

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