A STUDY ON GROWTH PERFORMANCE AND VIABILITY OF THREE MARINE FISH SPECIES UNDER CAGE CULTURE IN THE KENYAN COAST

Abstract

This study set out to investigate and compare the growth performance and viabilities of three different marine fish species for commercial cage culture. The study was carried out in Makongeni village along Kenya coast from April 2012 to November 2012 with three marine species: maze rabbit fish (Siganus vermiculatus Valenciennes, 1835), red snapper (Lutjanus argentimaculatus) and milk fish (Chanos chanos). The experiment consisted of 12 floating cages, four cages for each species and each cage holding a total of 50 juvenile fish of weight between 50-70 gm, reared for six months. Monthly variations of mean weight for each species in each of the cages show that milkfish had the highest final body weight (150.4 ± 4.8 g); whereas rabbit fish had the lowest final weight of 101 ± 3.63 g. The final mean length for each species also show that milk fish had the highest final mean total length (24.1 ± 0.53 cm) followed by rabbit fish (19.5 ± 0.52 cm) and lastly by red snapper (17.5 ± 0.22 cm). The growth parameter were L∞ of 45.53, 37.96 and 20 cm for milkfish, rabbit fish and red snapper respectively while the corresponding growth constant (K) were 0.398, 0. 526 and 0.729 respectively. The growth performance index was highest for milkfish (=1.71 and ‘=2.92) while the Specific Growth Rate (SGR) was also highest for milkfish (0.65%) as compared to rabbit fish (0.53%) and red snapper (0.33%). The length weight relationship showed a positive allometric growth for milk fish (b=3.8; R2=0.800) and negative allometric growth for both red snapper (b=1.7; R2=0.811) and rabbit fish (b=2.8; R2=0.895). The best Feed Conversion Ratio (FCR) was obtained in milk fish (4.45 ±0.65) and highest in red snapper (10.56 ± 1.12). Rabbit fish on the other hand recorded an FCR of 6.04 ± 0.71. Milkfish had high mortality and low survival (81%) as compared to rabbit fish (93.5%) and snapper (91%). Milk fish were found to be more viable compared to other two at a net profit of KShs. 914.00. Based on the results of growth rate, feed conversion ratio, survival and economic viability, it is concluded that milkfish is the best candidate for culture as compared to the other two test species. Intensive pilot culture of milk fish should be undertaken in cages, develop an enterprise budget and business plan for commercialization with parallel research and development of suitable feeds.