Effects of aflatoxin contaminated feed on the fingerlings of tilapia (Oreochromis niloticus Linnaeus, 1758)

Aflatoxin contamination, particularly common in cultured fishes in Asian countries, are considered unsafe both for fish and human health. However, the presence of aflatoxin in cultured fish feed and their effect are still under estimated in Bangladesh. The present study aimed to assess the effects of aflatoxin on growth performance and residues in tilapia (Oreochromis niloticus) fingerlings. Fish feed were treated with several concentration of aflatoxin as 0 ppb (T0, control), 25 ppb (T1), 50 ppb (T2) and 100 ppb (T3) and fed the tilapia fingerlings (n=10) in individual glass aquaria (24×12×12 inch, 105-litre capacity) conditions for 12 weeks. Comparatively higher body length (cm) and weight gain (g) were observed in treatment T0 (1.68 and 4.98) and T1 (1.60 and 5.48) than those of treatment T2 (1.31 and 4.06) and T3 (1.20 and 3.10), respectively. The specific growth rate (SGR) were almost similar in treatment T0 (52%), T1 (51%) and T2 (52%) whereas declined significantly (p<0.05) in T3 (39%). Higher survival rate was also demonstrated in treatment T0 (90%) and T1 (90%) whereas significantly decreased in treatment T2 (60%) and T3 (40%). The residue of aflatoxin was not detected in T0 and T1. On the contrary, the residual effect in tilapia fingerling was evident in T2 and T3 treatment. The findings of the present study revealed that aflatoxin contaminated feed is harmful for the growth performance and survival of O. niloticus fingerlings. Further study is necessary to safeguard the aquaculture production as well as to produce healthy food for human consumption

Biochemical, Microbiological, and Sensory Properties of Dried Silver Carp (Hypophthalmichthys molitrix) Influenced by Various Drying Methods

An experiment was performed to evaluate the effects of different drying methods with different pre-treatments on the physico-chemical, microbiological, and sensory properties of the silver carp, Hypophthalmichthys molitrix. In order to achieve this objective, the collected fresh fish were dried using traditional (without any pre-treatment), improved (fish soaked in a 5% salt solution for 10 min and then treated with chili powder (0.3%) and turmeric powder (0.3%)), and solar tunnel (fish soaked in a 5% salt solution for 10 min) drying methods. The results showed that the dried fish produced by the solar tunnel drying method were rehydrated more rapidly than the products produced by the traditional and improved drying methods. The moisture content of the dried H. molitrix was varied from 18.24 to 25.43% on a fresh matter basis. There was no significant (p > 0.05) difference found regarding the protein, lipid, and ash content among the different drying methods on a dry matter basis. The total volatile base nitrogen (TVB-N) contents ranged between 37.58 and 45.03 mg/100 g, and significantly (p < 0.05) the lowest TVB-N was observed in dried fish produced by the solar tunnel drying method. Moreover, the highest peroxide and acid values were found in the traditionally produced dried fish as compared with the fish dried by the improved and solar tunnel drying methods. The aerobic plate count of dried fish ranged from 4.52 to 7.51 log CFU/g. The sensory evaluation results revealed that the solar-dried products showed superior quality than the products produced by the traditional and improved drying methods. The results revealed that the dried fish produced by the solar tunnel drying method provided the best product in terms of physico-chemical, microbiological, and sensory aspects