Abstract
To investigate iterative measurement of the morphometric characters of fish larva, the daily change in the body size of intensively reared larval fish, red sea bream snapper Pagrus major, olive flounder Paralichtys olivaceus and ayu Plecoglossus altivellis was monitored on the moribund state and over the subsequent preservation process of 15 days and the differentiation by formalin fixation was evaluated.
Throughout the trial period the size of the fish body frequently suffered significant shrinkage and/or weight loss immediately after fixation and then slightly but chronically in the fixative. Primarily the weight loss was more pronounced than the shrinkage in length. An Analysis of the covariance for the allometric equations, therefore, suggests that the treatment of fixed samples might be misleading when conducting morphometric studies of live fish stock. The changeability of physical body was dependent upon age, even though the somatic sizes were of an equivalent range when alive. Moreover, the variation in measurements over one hour or so mostly occurs irrespective of the formalin fixation. These facts suggest that iterative measurements of fixed fish larva are limited and alternative methods such as applying microscopic biophysics to the variations in the structure and tissues of larval fish in fixatives, or using optical and volumetric techniques for live measurements are required.
