No abstract

A study to evaluate the effects of the preservative, Actellic 25 EC solution, on the mineral composition of the three freshwater fish species was carried out. Pieces of fish (samples) were analysed for mineral composition before and after traditional smoke drying and smoke drying after Actellic treatment. The investigations were carried out using fresh water fish, Heterobranchus longifilis, Heterotis niloticus and Chrysichthys nigrodigitatus. The result showed that Actellic 0.03 % solution greatly reduced the sodium content of the smoked dried fish species. Furthermore, Actellic 25 EC eroded the magnesium (Mg) content of C. nigrodigitatus and also reduced slightly the naturally high iron content of H. longifilis, H. niloticus and C. nigrodigitatus. The implications of these results are discussed.

The fecundity of four batch weights (10 samples each) o gravid Clarias gariepinus weighing 60 ± 0.17159 g 125 ± 0.15092 g 250 ±0.20683 g and 500 ± 0.15670 g raised from the hatchery was investigated The paired ovary of each fish was dissected out, weighed (g) and its length measured (mm). Each paired ovary was stored n a solution of 1 % formalin in 0 6 % saline solut on for at least 3 weeks for the solution to harden the eggs and remove egg clumping. After 3 weeks, each paired ovary was torn apart on a 2 mm mesh circular fabricated sieve over a stream of water. The eggs passed through the 2 mm mesh sieve into a receptacle. Sub sample of the eggs from each paired ovary was taken, counted and all the eggs in each paired ovary were determined thereafter by volumetric method. The tota fecund y of 40 gravid f sh stud ed ranged rom 6,450 to 71,450 eggs per f sh. The mean fecundities of the 60 g 125 g, 250 g and 500 g f sh were 8,501.9 ± 295.5, 13,364.0 ± 1734.3, 41 087.9 ± 12258.1 and 51,186.0 ± 13851.0 eggs respect vely. The relationships between fecundity and fish weight (FW) (n = 40, r = 0.8761), f sh ota leng h (TL) (n= 40, r = 0.8266), f sh ovarian we ght (OW) (n = 40, r = 0.7609), fish ovar an length (OL) (n = 40, r = 0.7236), gonadosomatic index (GSI) (n = 40, r = 0.5992) and f sh cond t on factor (K) (n = 40, r = 0.9046) obta ned were linear and positive and the condit on factor appeared to be the best predictor of fecundity in C. gariepinus studied. The higher fecundity o C. gariepinus (range: 6,450 to 71 450) obta ned from th s study when compared w th the range of 9,000 to 25,000 earlier reported from the wild stock indicates that hatchery-raised C. gariepinus is more fecund than the wild fish in the Anambra area of the sub-region. Therefore, hatchery-raised C. gariepinus appears to be better for fish breeding in fingerl ngs production than the wild fish.

This paper describes the growth response of the developmental stages of hybrid cat ish resulting rom the crossing of Heterobranchus bidorsalis (male) and Clarias gariepinus (female), fed with different feed rations. Hatchlings of the hybrid catfish were cultured in plastic aquaria set up at the fish hatchery complex, Nnamdi Azikiwe University, Awka. The hatchlings were fed and observed for 91 days. Different food items such as artificially compounded feed, zooplankton / live organisms Moina sp and Brachionus sp, and a mixture of zooplankton (Moina sp and Brachionus sp) and artificially compounded feed were administered. The mixture gave the best result with a mean weight o 7 92g ± 2.73g fo lowed by those fed Moina sp (1.93g ± 0.27) and Brachionus sp (1.80g ± 0.32) respectively. Hatchlings fed only artificially compounded feed exhibited the poorest growth. A mixture of live food organisms and art cially compounded feed is thus recommended for better growth response of catfish hybrid, (H. bidorsalis ♂ x C. gariepinus ♀). f f , f . , l ifi r

A study to evaluate the effects of insecticide, Actellic 25 EC and salt solutions on proximate composition, preservation of organoleptic properties and reduction of insect infestation on traditionally smoked dried fish samples was carried out using three freshwater fishes, Heterobranchus longifilis, Heterotis niloticus and Chrysichthys nigrodigitatus. The various dehydration and smoking treatments had effect on the proximate composition. The highest moisture contents were recorded in the batch I (fresh) fish pieces, while the lowest moisture content occurred amongst the Actellic dehydrated and smoked dried fish pieces. The fat content of fish pieces dehydrated and smoked dried showed that the non dehydrated and non smoked dried fish pieces (fresh fish) had the highest fat content. The highest fibre content was recorded in the batch I (fresh fish) fish species and the lowest was recorded among the fish pieces dehydrated in salt solution before smoke drying. The protein content of fish pieces variously dehydrated and smoked dried revealed that the Actellic 25 EC dehydrated smoked dried fish pieces had the highest protein content while the lowest protein contents were recorded among the fresh fish pieces not dehydrated either in salt and/or Actellic 25 EC solutions. The highest carbohydrate content was recorded in the batch I (fresh fish) while the lowest occurred among Actellic 25 EC dehydrated smoked dried fish pieces. Two insects, Dermestes sp and Necrobia sp were identified to attack dehydrated and smoked dried fishes. The smoked dried fishes had comparatively higher insect attack than the salted and / or Actellic dehydrated smoked dried fish pieces. Fish pieces preserved with Actellic had the overall best organoleptic properties while acceptability of the dried fish was best for salted smoked dried fish pieces. The relevance of this study to humanity is discussed.