Effects of Different Tank Sizes on Laboratory Rare Minnow (Gobiocypris rarus)-Under the Same Density

Laboratory fish play an important role in many research fields, and they are also raised and bred in many laboratories around the world. While many studies have suggested suitable feeding densities for various laboratory fish, significant variations exist in the sizes of rearing tanks across different laboratories. Moreover, there is limited research on the effects of different rearing tank sizes. In this study, we set up the same rearing density (one liter of water corresponding to two fishes) and four treatments with different tank sizes (5 L, 10 L, 15 L, 20 L). We found that different sizes of rearing tanks had no significant effect on the growth and shoaling of laboratory rare minnow. However, the rare minnow in 10 L tank had lower cortisol levels, while the rare minnow in 20 L tank had higher levels of dopamine (DA), serotonin (5-HT) and their metabolites (DOPAC and 5-HIAA). These results show that even under the same rearing density, different sizes of rearing tanks will still have a physiological effect on the rare minnow, and the tank size suitable for laboratory fish should be considered.