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Formalin is an effective solution for surface and equipment disinfection and also for several aquaculture industry challenge. Since various aquatics have different sensitivity to this substance, determination of a precise concentration for cultured fish is important. Because of diversity in aquarium fish species, this topic more highlights. In this study, the method of The Organisation for Economic Co-operation and Development (OECD) were used for LC₅₀ of formalin solution (%37) in Zebrafish.
Six concentrations of this solution; 200, 213.98, 228.94, 244.99 and 262.07 mg/l plus a control group and three repeats for each group were applied. Mortality was recorded daily and at the end of 96 hours, LC₁₀, LC₅₀, and LC₉₀ and the results were calculated (Probit Analysis method) 199.21, 255.57 and 327.89 mg/l respectively. Maximum safe concentration, MIC and ineffective concentration of formalin were obtained 25.56, 199.21 and 25.26 respectively for zebrafish. In order to the results, zebrafish has a good resistance to formalin solution.

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The present research conducted within 8 weeks, aimed at examining the impacts of white worm (Enchytaerus albidus) on the growth function of Goldfish fry (Carassius auratus). Therefore, the effects of mixed experimental diet A (30% white worm/ 70% dry feed) and the control diet B (100% dry feed) on Goldfish fries (150±2.21mg) were determined in two treatments and three replicates. At the end of feeding phase, weight gain percentage (%), daily growth (%), daily weight gain (mg), FCR, protein efficiency (g) and SGR (%) were calculated in both groups. The results revealed that all growth related indices in the fries fed with mixed diets stood higher than those of in the control .(P≤0.05). The study also showed that the inclusion of white worm (Enchytaerus albidus) in the diet of Goldfish fries improved their weight gain.