Silver crucian carp, Carassius langsdorfii, a triploid gynogenetic fish were collected from the Niyodo and Monobe Rivers, Kochi prefecture, Japan.Clonal lines were identified by genetic markers such as isozyme patterns (PROT, CK, PGM, GPI, EST), DNA fingerprinting and RFLP of the D-loop region of mtDNA. A total of 17 clonal lines were detected by DNA fingerprinting and isozyme genotypes. Six clones were common to both rivers, with ten and one being restricted to the Niyodoand Monobe Rivers, respectively. In RFLP analyses of the D-loop regionofmtDNA, eight haplotypes were detected, one to the four clones beingincluded ineach. Average haplotypic diversity (h) among the clonal lines wasrelatively hig (0.782) in RFLP, whereas the average inter-clonal BSI was low (0.195) in DNA fingerprinting. The factor responsible for the high geneticdivergence among the 17 silver crucian carp clones was discussed from the view points of their clonal nature and gynogenetic reproduction.
Mating, the spawning cycle, embryonic development and growth of the white spotted bamboo shark, Chiloscyllium plagiosum, were observed in an aquarium. Mating, which continued for about five minutes, was observed twice in February and May, 1993. Premating behavior included the male shark swimming with the female for thirty minutes, biting the pectoral fin of the latter. From spring to summer, two eggs were deposited at each spawning, the latter occurring every 6 or 7 days on average. After mating, the female shark was separated from the male. Fertilized eggs were produced for about two to five months after copulation, apparently due to sperm storage and delayed fertilization. The average hatching period was 128.2 days. The total length and weight of young at birth averaged 16.6 mm, and 15.5 g, respectively, the former reaching 30 cm after one year.
Six specimens of a scorpaenid fish, Scorpaenodes varipinnis (15.9-42.0 mm SL) were captured from the coral reefs of the Ryukyu Islands at depths of 10-20 m. This is the first occurrence of the species from the main Japanese Archipelago, although it has recently been recorded from the Ogasawara Islands. Scorpaenodes varipinnis is distinguished from other scorpaenids by having the following combination of characters: 13 spines and 8 soft rays in dorsal fin, no teeth on palatine, a dark blotch on the posterior area of the dorsal spinous part, and a dark crescent-shaped marking on the basal region of pectoral fin. Six proportional measurements (head length, interorbital width, spinous dorsal fin base length, 11 th and 12th dorsal spine lengths, and 3rd anal spine length) showed allometries. Lateral line scales were incomplete on the caudal peduncle in the smallest three specimens (15.9-19.1 mm SL).
A deformed individual of the spotted parrot fish Oplegnathus punctatus, lacking the caudal fin, was caught by a set-net off Obama, Wakasa Bay in the Sea of Japan, on September 25, 1995. An X-ray photograph indicated that the specimen was missing the last two and half centra together with the entire caudal skeleton. The surface of cut-end was healed and covered with skin. The posterior parts of dorsal and anal fins were elongated vertically.
The feeding behavior of Asterorhombus intermedius was describedfrom aquarium observations. When frozen krill placed in the tank had descendedto the bottom, the fish would approach it to within. 10 cm, at that point lifting its first dorsal-fin ray to an angle of 45°, before returning it to its original position viaa sideways movement to an angle of 45° from the vertical plane. On completion of the fin movement, the fish continued to move toward the food, suddenly darting to it over the final 1.5 cm. The rotary motion of the first dorsal-fin ray of A. intermedius appeared to have a significant role in that species' feeding behavior.