Induced spawning of African cat fish Clarias lazera (C. and V.) using acetone dried carp pituitary extract, deoxy-corticosterone acetate and human chorionic gonadotropin

A study was conducted to determine the efficacy of carp pituitary extract, deoxycorticosterone acetate, and human chorionic gonadotropin in inducing spawning in Clarias lazera . Results indicate deoxycorticosterone acetate to be more potent than pituitary extract, although the difference is not significant

The influence of diets and body manipulations on the growth of African prawn Macrobrachium vollenhovenii (Herklots)

Live African prawns Macrobrachium vollenhovenii were collected from Asejire reservoir (Nigeria) by trapping. After acclimatization, the prawns were differently amputated: some had their eye-stalks cut; some had their chelae cut; some had both eyestalks and chelae cut while some were intact which served as the control. Each set was placed under different levels of crude protein viz 15%; 20%; and 25%. Weekly weight changes were monitored. Results obtained were subjected to statistical analysis including analysis of variance (ANOVA). The results showed that prawns fed with 20% crude protein had the best growth rate. Specimens with the eyestalk and chelae removed also showed superior growth when compared with the others. Specimens that had their eyestalks removed were able to feed for 18 hours in the day while those with intact body fed for 6 hours during the same period. The amputation of the chelate appendages reduced considerably the cannibalistic urge in the prawns. This enabled a high number of prawns to be grown in the experimental tanks

Food composition and digestive enzymes in the gut of the African electric catfish Malapterurus electricus (Gmelin 1789) (Malapteruridae)

Analyses of stomach contents of 330 Malapterurus electricus (standard length, 10.1-30.5 cm) in Mahin Lagoon (southwestern Nigeria) established it as a bottom feeder. There was a preponderance of insects accounting for >80% occurrence and >25% of total volume in stomachs of specimens, suggesting a stenophagous predatory habit. Qualitative and quantitative assays of digestive enzymes in the different regions of the gut (oesophagus, stomach, duodenum, ileum, rectum) were investigated. Carbohydrases (amylase, maltase), chitinase, proteases (pepsin, chymotrypsin, trypsin) and lipases were detected in different gut regions with different activity. The pattern of distribution and relative activity of the enzymes correlated with the predatory diet

Successful handstripping of hatchery bred and reared male African catfish, Clarias gariepinus (Burchell, 1822)

A total of 45 Male and 5 female Clarias gariepinus bred and reared in the hatchery in sunning for one year were obtained for this experiment. The fish were then housed separately according to their sexes and maintained on trout diet at 10% body weight for two days before they were subjected to induction. These were then induced using both human chorionic gonadotropin (hCG - 500iu) and carp pituitary suspension (CPS -3mg kg super(-1) suspended in 0.9% saline) either as priming or resolving doses. The milt produced was used to fertilize eggs tripped from females. The results indicated high milt production, motility and fertility in most males

The analysis of dieldrin residues in the brain, liver and muscles of the African catfish Clarias gariepinus (Burchell 1822) chronically exposed to dieldrin

Mature adult Clarias gariepinus were obtained at the ABRU hatchery in Sonning (UK), where they had beenbred and reared for several years. These were exposed to two concentrations of dieldrin in water (2.4 mu g super(-1) and 4.0 mu g super(-1). The residue analysis of diedrin in three tissues exposed for on moth at two concentrations was carried out. These were subjected to GLC analytical process. The results indicated significantly (P<0.05) higher residues in liver than in muscle and brain. The results also showed that residue levels were dependant on exposure concentration

Assessment of consumer acceptance of kilishi of African carp (Labeo coubie Rueppell) and Elephant snout (Hyperopisus bebe occidentalis, Guenther)

This study was carried out to assess consumers' acceptance of kilishi prepared from Labeo coubie and Hyperopisus bebe occidentalis in Sokoto. The organoleptic properties (texture, odour, taste and flavour) of kilishi in its fresh form and under storage for 16 weeks were determined. The mean scores for the organoleptic assessment (6.90 and 7.19 for kilishi of Labeo and Hyperopisus respectively) showed that fish kilishi was highly acceptable. Hyperopisus kilishi recorded slightly higher mean scores for the tested organoleptic properties. The declining pattern of the sensory assessment scores with length of storage indicated that the optimum storage period under the room temperature for kilishi made from the experimental fish species in the study area was 6-8 weeks. Further research on appropriate storage methods is desirable. However, preparation of fish kilishi could be explored as alternative preservation technique to reduce fish spoilage especially during the glut in supply and to diversify fish products