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This trial was conducted to assess the possibility of replacing maize (Zea mays L) with varying levels of whole cassava (Manihot esculent crantz) root meal (WCRM) in the diet of hybrid catfish (Heterobranchus, bidorsalis x Clarias gariepinus). The effect of replacement on growth variables and nutrient utilization of the WCRM as a replacement for maize were also determined. Four practical diets with varying replacement levels of maize at 0 (A o), 33 (B 33), 66(C 66), and 100% (D 100) were formulated and fed to hybrid catfish fingerlings for 32weeks. Fish were fed twice daily at 5% body weight/day. Optimum growth, nutrient utilization of the fish were assessed. The results obtained from the study indicated that WCRM can completely replace maize with the best result at 66% inclusion. The highest values of growth performance were: final weight 12,782±601.21g, mean weight gain 12041.43±312.66g, and daily weight gain 78.78±10.28g. The nutrient utilization indicated the best feed conversion ratio (FCR) 1.71±0.40; Gross feed conversion efficiency (GFCE), 68.95±5.161; protein intake (PI), 12975.88±306.11g, protein efficiency ratio (PER) 1.98±0.11; and nitrogen metabolism (NM) 10782.98±314.12g/100g were recorded in diet C 66. However, growth and nutrient utilization variables varied significantly (p<0.05) within the treatment period. The mean final weight, FCR and PER of the fish fed trial diets were not significantly different (p>0.05) from the control value. Dietary WCRM at 100% inclusion produced similar results in the mean weight gain (MWG), mean daily weight gain (MDWG), Gross Feed Conversion Efficiency (GFCE), Protein Intake (PI), and survival as the control diet. It could therefore be concluded that WCRM can replace maize in the diet of hybrid catfish effectively up to 100% with the optimal performance at 66% level of inclusion. Fish farmers can therefore explore the use of WCRM as an alternative to maize meal in hybrid catfish diet with better profit margins.

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Mycotoxins are secondary metabolites produced by filamentous fungi that could cause toxic responses when ingested by animals. The extent of production varies with geographic location, feed storage practices and processing methods. In the tropics, improper bagging, transport, storage and use of feeds with inferior quality of ingredients are ways in which mycotoxin is produced and is a great challenge that threatens life of culture fish. Mycotoxins in feeds are a problem of significant concern as farmers are taking steps to overcome the challenge of feed supply. The effects result in teratogenic, carcinogenic, oestrogenic or immune-suppressive effects, poor growth, low apparent digestibility, physiological disorders, histological change and death. The expression of mycotoxin impacts is influenced by factors such as age, nutrition, sex, species and the possibility of concurrent exposure to other toxins. The main target organ in animals is the liver; therefore, mycotoxin disease is primarily hepatic. Conditions increasing the likelihood of mycotoxin impacts in aquatic organisms include limited feed availability, environmental conditions that favour mould growth on feedstuffs, and lack of regulatory systems for aflatoxin monitoring and control. Mycotoxin's effect on these organisms is not only on health problems in exposed fish but also represents a high risk to consumers through residues in fish musculature. Therefore, control and prevention measures are needed to sustain the aquatic resources. However, several effective ways to prevent and control hazardous fungi and their dangerous mycotoxins have been presented.