Procedure for Harmless Estimation of Fish Larvae Weight

Abstract

The aim of this study was to evaluate a procedure of weighing live fish larvae and to determine its impact on the survival and growth rates based on the example of ide Leuciscus idus (L.). A 14-day rearing was conducted. Larvae were randomly divided into two groups – control (C) and experimental (E). During the experiment, 10% of larvae from the E group were sampled and weighed (with experimental method) daily. An integral part of weighing method was to place the anaesthetized larvae onto a nylon net platform. The platform with larvae was then dried on the blotting paper and next weighed together with larvae. The weight of the larvae was calculated by deducting the weight of the platform from the total weight recorded. After weighing, the fish were returned to the rearing tank. Fish from the control group were not manipulated during the whole experiment. At the end of the experiment 90 randomly chosen fish from each group were measured and weighted. No significant differences were recorded in larvae survival, weight and length (91.33±4.73%; 41.69±10.70 mg; 17.56±1.44 mm and 94.00±4.00%; 49.40±10.79 mg; 18.41±1.24 mm in E group and C group, respectively). Significant differences were recorded in case of SGR that reached 15.80±0.29 in C group and 14.60±0.17 in E group. The described method may be a useful tool for determining fish larvae weight. Although it requires conducting further researches in order to establish the influence of accompanying factors such as e.g. kind and concentration of anaesthetic.