The use of prebiotics and probiotics as feed supplements that improve efficiency of intestinal bacteria is becoming de rigueur in animal husbandry in many regions worldwide. We tested the effects of a commercial probiotic (Biogen Ò ) containing allicin, high unit hydrolytic enzyme, Bacillus subtilis spores and ginseng extracts on survival, growth, carcass composition and feed cost/benefit in rabbitfish Siganus rivulatus. Fifteen net cages (100 · 100 · 40 cm; L · W · H) were stocked with 10 juvenile rabbitfish (10.3 g per fish) each and placed in a large rectangular tank and offered feed at 4% body weight daily. Cages were offered one of five isonitrogenous and isocaloric diets containing 0, 1, 2, 3 and 4 g kg )1 probiotic at three replicates per treatment for 98 days. Fish in all cages were weighed at 2-week intervals and feed regimen was adjusted accordingly. Rabbitfish offered the control diet exhibited lower growth and feed utilization than all experimental treatments. There was no effect of probiotic inclusion level on survival but growth was better at all inclusion levels than in the control. No significant differences (P > 0.05) in growth were observed among fish groups fed various levels of the probiotic. Carcass composition was not affected by dietary probiotic inclusion. Ultimately, when all variables are considered, Biogen Ò inclusion to diets appears to reduce feed cost per unit growth of rabbitfish. KEY WORDS

A 60-day feeding study was performed to evaluate the role of dietary commercial wood charcoal (CWC) in fish growth performance, body composition and water quality of fingerlings red tilapias (Oreochromis mossambicus 9 Oreochromis niloticus). Four levels of charcoal (10, 20, 30 and 40 g kg À1 ) were added to the control diet (0 g kg À1 CWC) and fed to red tilapias (initial weight of 1.20 AE 0.04 g). At the end of the feeding trial, the fish weight gain, specific growth rate, feed conversion ratio, protein efficiency ratio and energy retention of the fish groups fed 30 and 40 g kg À1 (CWC) in diet were significantly (P < 0.05) higher comparing with all other tested fish groups. Moreover, some proximate composition such as crude protein and nitrogen retention efficiency g kg À1 of the fish groups fed on 30 and 40 g kg À1 CWC diets showed higher values (P < 0.05) than those of other tested fish groups (0, 10 and 20 g kg À1 CWC). Apparent digestibility coefficients of protein and dry matter were improved (P < 0.05) in CWC-tested fish groups compared to the control fish group. These data were powered by the data of the water quality that showed significant (P < 0.05) enhancement in both dissolved oxygen and ammonia concentrations by the increment in dietary charcoal levels. The above-mentioned parameters' data suggested that 30 g kg À1 dietary CWC can be considered as a suitable level to maintain normal growth of red tilapia juveniles as well as to enhance water quality of the rearing area.

Rabbit¢sh are an Indo-Paci¢c herbivorous marine ¢sh that have good market demand and are suitable for aquaculture. The present work was performed to determine dietary protein inclusion necessary for optimal growth of juvenile rabbit¢sh Siganus rivulatus. Six diets with increasing levels of protein (10, 20, 30, 40, 50 and 60 g crude protein 100 g À 1 feed) and similar levels of gross energy (20 MJ kg À 1 ) were prepared and o¡ered to S. rivulatus juveniles maintained in triplicate cages placed in two large water tanks for 49 days. Growth progressively improved with dietary protein for ¢sh o¡ered diets from 10% to 40% protein inclusion. Diets with greater protein levels did not improve ¢sh growth beyond that observed in the 40% group. Daily feed intake, apparent protein utilization and feed conversion ratio decreased as dietary protein increased. Protein e⁄ciency (PE) was greatest (1.47) in ¢sh o¡ered the 10% protein diet and least in ¢sh o¡ered the 60% protein diet (0.80). No di¡erences in PE were observed among all other treatments (20^50%). Results of the present work suggest that minimum dietary requirement for suitable growth of S. rivulatus juveniles is 40% protein when digestible energy of the diet is 16^18 MJ kg À 1 .

No abstract

No abstract