Quantitative estimation of maximum daily feed intake of African catfish, Clarias gariepinus Burchell, fingerlings using radiography

Gastric evacuation rate, return of appetite and satiation time of African catfish, Clarias gariepinus Burchell 1822, fingerlings, fed with a commercial pelleted feed, were determined under experimental conditions. The gastric evacuation rate was described by an exponential function, which was found to be inversely related to the rate of ingestion (return of appetite). Satiation time remained constant over the experimental period. Based on these data the authors estimated maximum daily ration in relation to feeding schedule and feeding frequency for C. gariepinus fingerlings.     

Evaluation of mixed feeding schedules with respect to compensatory growth and body composition in African catfish Clarias gariepinus

An 8‐week feeding trial was conducted in a recycling water system at 28 ± 1 °C to investigate compensatory growth and body composition in African catfish Clarias gariepinus (13.05 ± 0.05 g). A fishmeal‐based diet containing 350 g kg^?1 protein and 17.5 kJ g^?1 gross energy was fed to triplicate groups of 20 fish (per 30‐L tank). Fish were fed the diet either to satiation or feed restricted in six feeding schedules as satiation 56 days; restricted 28 days + satiation 28 days; restricted 14 days + satiation 14 days; restricted 7 days +satiation 7 days; restricted 3 days + satiation 4 days; and restricted 2 days + satiation 2 days. The restricted regime was achieved by offering fish 1% (maintenance ration) of their body weight per day adjusted after fortnightly weighing. African catfish showed partial compensatory growth under alternating periods of feed restriction and satiation feeding with significantly different values (P < 0.05) from fish fed in satiation throughout. However, significantly indifferent (P > 0.05) values of feed, protein, lipid and energy utilization were found under alternating periods of feed restriction and satiation feeding. Significantly higher (P < 0.05) feed intake was observed in treatment with satiation throughout than those in other treatments. All the feeding schedules showed no significant differences (P > 0.05) on body composition, organ indices, eviscerated carcass composition, viscera lipid and liver lipid. These studies reveals that C. gariepinus showed partial compensatory growth responses at alternating periods of restricted and satiation feeding.     

Urea and ammonia excretion by embryos and larvae of the African catfish Clarias gariepinus (Burchell 1822)

Yolk-sac larvae and starved larvae of Clarias gariepinus (Burchell 1822), reared at 28°C, were predominantly ammonotelic, but urea excretion contributed about 19±7% to the total nitrogen excretion. Exogenously feeding larvae of C. gariepinus were mainly ammonotelic until 180-205 h post fertilization, but from then on the relative urea excretion stabilized at 44±13%. The contents of total free amino acids (FAA) and ammonia in C. gariepinus peaked around complete yolk absorption. During the first period after hatching 64% of the FAA and 60% of the total ammonia were located in the yolk compartment. The body compartment contained the highest amount of FAA and total ammonia at the end of the yolk-sac period (65 and 77%, respectively). The amount of nitrogen originating from catabolism of amino acids was balanced within 6% by the excreted sum of ammonia and urea. The high degree of ureotelism in C. gariepinus larvae may constitute an adaptive mechanism to a habitat of temporal water shortage.     

The influence of food particle size on gastric emptying and growth rates of fingerling African catfish, Clarias gariepinus Burchell, 1822

This study investigates the effect of feed particle size on gastric evacuation and growth of fingerling African catfish, Clarias gariepinus . Fish (0.97 ± 0.07 g) held in 40-cm diameter tanks at a stocking density of 5 fish L^–1 (25 fish per tank) were presented with one of four sizes of food particles (1, 1.5, 2 and 3 mm diameter). Gastric evacuation rate could be described by an exponential function with small feed particles being evacuated more rapidly: values of 0.076, 0.054, 0.047 and 0.029 were observed for fish fed 1 mm, 1.5 mm, 2 mm and 3 mm food particles, respectively. Growth rates were highest for fish fed the 1.5 and 2 mm pellets. Based on these findings, recommendations are made on the optimum food particle size for C. gariepinus fingerlings.     

Effect of feeding time and frequency on the growth and feed utilization of African catfish Clarias gariepinus (Burchell 1822) fingerlings

The effects of feeding time and frequency on the growth, feed utilization and survival of Clarias gariepinus (Burchell 1822; family Clariidae) fingerlings were evaluated in a 25-day study. Groups of African catfish with an initial individual weight of 0.98 ± 0.02 g were offered feeds continuously for 24 h, or during the day or night at different time intervals, with varying meal size. The growth rate was significantly affected by meal times. Widely practised day time feeding with three equal size meals a day gave the lowest growth and highest food wastage. The growth rates of fish fed continuously or during night time following their feed demand were significantly higher with lowest food conversion ratios and food wastage.     

An evaluation of radiography in studies of gastric evacuation in African catfish fingerlings

Groups of 3–4 g African catfish (Clarias gariepinus Burchell, 1822; Family: Clariidae) were offered feeds of two types in three combinations: feed with a radio-opaque marker (Ballotini, 0.16–0.25 mm), feed without marker and a 50:50 mixture of marked and unmarked feeds. Stomach contents were estimated by X-radiography and gastrectomy just after meal termination and at different time intervals (4, 8, 12, 16, 20, 24, 32, 40 and 48 h). There were no significant differences among treatment groups confirming that there was no effect of the marker on feed preference and evacuation rate. Estimations of gastric evacuation rate calculated from gastrectomy and by X-ray sampling were not significantly different. Therefore, gastric evacuation rate of African catfish can be accurately estimated by feeding marked feed and then using X-radiography to monitor feed passage through the gut. © Rapid Science Ltd. 1998     

A Review of Feeding Practices, Growth and Nutritional Physiology in Larvae of the Catfishes Clarias gariepinus and Clarias batrachus

A comparative study of larval growth in the different species of the genus Clarias in different regions revealed that in spite of strong differences in egg and larval size, the growth potential was quite similar. Differences in growth between species and regions were strongly correlated with the applied feeding strategy, the applied growth parameter and period of measuring. To evaluate feeding strategies, standardized procedures for measuring growth are needed. Recalculating the results of the mentioned study according to these standardized procedures revealed that both in India and Indonesia, the growth rate of C. batrachus larvae was too low. This is probably due to low feeding levels in India and premature weaning in Indonesia.
The basic biology and nutritional physiology of the larvae of C. gariepinus have been studied extensively. At the start of exogenous feeding, the larvae have an advanced digestive system with a functional pancreas, liver and nutrient absorption capabilities, but lack a functional stomach. The advanced digestive system is further exemplified by the development of the enzymatic complex. Probably because of the rapid development of the digestive system, feeding live food organisms is mostly practiced for a few days only and is soon replaced by wet and/or dry diets. It is hypothesized that the requirement of live food or specific larval diets during the first days of exogenous feeding is related to the absence of pepsin digestion during this period. Further optimization of the feeding strategies should focus on this conclusion.     

Optimum histidine requirement of fry African catfish, Clarias gariepinus (Burchell)

Dietary histidine requirement of fry African catfish, Clarias gariepinus (2.57 ± 0.02 cm; 0.22 ± 0.03 g) was quantified by feeding casein–gelatin-based isonitrogenous (40% crude protein) and isocaloric (17.90 kJ g⁻¹ gross energy) amino acid test diets with graded levels of histidine (0.25%, 0.30%, 0.35%, 0.40%, 0.45% and 0.50% dry diet) in eighteen 80 L indoor circular aqua-coloured troughs provided with the flow-through system for 12 weeks. Maximum absolute weight gain (2.66), best feed conversion ratio (1.29), highest protein efficiency ratio (1.94), protein retention efficiency (34%) and energy retention efficiency (70.4%) were achieved at 0.40% dietary histidine. Broken-line and non-linear regression models were adopted to assess dietary histidine requirement for C. gariepinus . When analysed using broken-line regression model these parameters were also best at 0.40% dietary histidine corresponding to 1.0% protein, respectively, whereas using second-degree polynomial regression analysis, histidine requirement was obtained at 0.42%, 0.41%, 0.40%, 0.41% and 0.41% of dry diet, corresponding to 1.05%, 1.02%, 1.0%, 1.02% and 1.02% protein respectively. Based on the broken-line and second-degree polynomial regression analyses of the growth and nutrient retention data, optimum histidine requirement of fry C. gariepinus was found to be in the range of 0.40–0.42% dry diet, corresponding to 1.0–1.05% of dietary protein.     

The consistency of individual differences in growth, feed efficiency and feeding behaviour in African catfish Clarias gariepinus (Burchell 1822) housed individually

Individual variation in growth, feed intake and feeding behaviour has been previously recognized in several fish species. However, there is a lack of information regarding the consistency of such individual differences, which is important to understand the probability of a certain individual trait to be inherent, i.e. genetically linked. The goal of this study is to quantify the consistency of individual differences in growth, feed intake/efficiency and feeding behaviour in African catfish Clarias gariepinus (Burchell 1822). Forty‐eight juvenile fish (58.9±0.4 g) were housed individually for 47 days and weighed every second week. The consistency of growth, feed efficiency (residual feed intake (RFI)) and feeding behaviour (total feeding time (TFT)) was determined using repeatability estimates. Fish exhibited pronounced individual variation in growth (CV=52.8%), feed intake (34.3%) and in the TFT (>100%). The repeatability estimates were 0.55 for growth, 0.70 for feed intake, 0.49 for RFI and 0.81 for TFT. Individual differences in growth were mainly explained by individual differences in feed intake (～80%). Individual differences in feeding behaviour contributed to explain differences in feed intake by affecting the RFI. With increasing TFT, the maintenance levels also increased suggesting that slow eaters were less efficient in feed/energy utilization. The results of this study indicate that individual differences in growth, feed intake/efficiency and feeding behaviour are consistent over time and therefore probably inherent. Moreover, this study may have implications on the use of feeding behaviour as a predictor of feed efficiency in juveniles of African catfish.     

Amino acid profiles and amino acid utilization in larval African catfish (Clarias gariepinus): effects of ontogeny and temperature

The present study investigated the qualitative amino acid (AA) requirements of larval African catfish Clarias gariepinus. Yolk-sac larval AA profiles were measured at different temperatures and also in animals reared at 28 °C fed Artemia nauplii or an experimental dry diet. The AA profile of C. gariepinus larvae changed during ontogeny, especially before the start of exogenous feeding. The AA profiles of the food items (yolk, Artemia and the dry diet) differed considerably from that of the larvae. No selective absorption of yolk AA was detected. Higher temperatures led to increased absorption and depletion rates of AA, and also to a higher retention efficiency of yolk nutrients. However, changes in temperature did not induce preferential absorption or depletion of individual AA, and caused only small variations in the AA profile. Depletion rates of individual AAs varied, possibly due to differences between larval and yolk AA profiles, and also to changes in the larval AA profile during ontogeny. There was little regulation of catabolism of individual AA in yolk-sac and starved larvae, and no sparing of essential AA.     

A dynamic simulation model for growth of the African catfish,Clarias gariepinus (Burchell 1822): III. The effect of body composition on growth and feed intake

A feeding experiment was conducted in aquaria to study the effect of body composition on growth and feed intake of Clarias gariepinus. Fishes weighing about 20 g were fed diets with different protein to fat ratios. Diet A contained 60% protein, 7% fat and 19% carbohydrate. The composition of diet B was 20% protein, 7% fat and 54% carbohydrate. After 4 weeks the mean fish weight per tank amounted 33.2±1.5 and 27.5±1.4 g for fish fed diets A and B, respectively, while the fat content of the fish was 3.6±0.3 and 6.1±0.4%.During two consecutive periods of 21 days both the lean and the fat fish were fed diet A or B at five feeding levels. The feeding levels ranged from maintenance to above satiation. Fresh weight gain, protein gain and fat gain were higher with increasing feed ration, until a maximum was reached where extra feed did not result in more gain. This maximum gain was higher for diet A. Feeding with this high-protein diet resulted in better feed conversions compared with diet B. Within one diet, lean fish had a higher maximum growth rate compared to fat fish due to a higher feed consumption. Below the maximum gain, fat fish showed a slightly better conversion efficiency when fed with diet A.A explanatory model, for simulating growth of C. gariepinus, was extended in accordance with these experimental findings. It is assumed that the maximum consumption is regulated by both lipostatic and glucostatic mechanisms. The relevant parameter values were fitted with results obtained in the second experimental period. The adjusted model was tested by comparing simulation with experimental results found in the third period. The model gives good results for feeding levels providing sub-maximum gain. At the highest feeding levels of diet A, fed to initially fat fish, the model overestimated gain. The model was used to predict fresh weight gain of C. gariepinus fed diets with different compositions.     

Controlled hatchery production of Clarias gariepinus (Burchell): growth and survival of larvae at high stocking density

Abstract. The mean increase in African catfish, Clarias gariepinus (Burchell), weight with time over the entire larval period can be approximated by a cubic or exponential growth model. However, the growth rate indices specific growth rate ( k ) and the regression coefficient of a cube root transformation of the weight data ( b ), both vary significantly when measured over successive short intervals from first feeding. In particular, the onset of air breathing is associated with a significant depression in growth rate. The variation in specific growth rate ( k ) with larval age closely approximates the relationship between mean % increase in body weight per day and larval age; however, the cube root regression coefficient does not share this property. In addition to the effect of larval age the growth rate of African catfish larvae is significantly affected by the initial density at which they are stocked (between 25 and 250 larvae/1) and interactions between age and stocking density. Survival over the larval period, of 80% or more, is apparently unaffected by initial stocking density (between 50 and 250larvae/I); however, the onset of air breathing in particular is associated with an increase in fish deaths.     

Effects of feeding frequency on the growth of young estuary grouper, Epinephelus tauvina (Forskål), cultured in floating net-cages

Studies on the effects of feeding frequency on the growth of young estuary groupers (Epinephelus tauvina) with initial size ranging from 16.2 to 16.9 cm in total length were conducted in floating net-cages. Seven feeding frequencies in the order of one feeding in 5 days, 4 days, 3 days, 2 days, 1 day, two feedings daily and three feedings daily were studied. Optimal growth and good food conversion ratio as well as higher survival rate were obtained in groups fed to satiation with one feeding in 2 days. Weight gains were substantially reduced in groups fed to satiation with one feeding in 5, 4 or 3 days and were not enhanced when the feeding frequencies were increased to two or three feedings daily. The fact that food conversion ratios were similar in fish fed to satiation with one feeding in 5, 4, 3 and 2 days suggests food intake to be important as a growth limiting factor. Total food intake per feeding was appreciably higher in fish fed once in 2 days. The intake of food was found to be closely related to the amount of food remaining in the stomach, intake being maximal when the stomach was empty. The food deprivation time in estuary groupers was found to be about 36 hours at which over 95% of the food was digested and less than 0.5% body weight of food remained in the stomach. Hence, feeding the fish at 48-hour intervals, i.e. once in 2 days, greatly enhanced maximum intake and efficient utilization of the food.     

Effect of microalga-based diet on oxidative stress enzymes of African catfish,Clarias gariepinus

Here an indigenously isolated microalgal strain Ascochloris spp. cultivated in synthetic medium was evaluated as an aquaculture feed supplement. The daily dietary supplement includes microalgal feed (AF) and commercial diet feed (CF) (as control), respectively. These diets were fed separately to the juvenile Clarias gariepinus fishes (n = 4) under controlled conditions for an experimental period of 100 days. The protein, glycogen and lipid contents in the muscle extracts were found to be marginally higher in fishes that were fed with CF than AF diet. Similarly, CF fishes showed significantly higher glutathione-s-transferase, catalase, superoxide dismutase, and lipid peroxidase activities, except glutathione content. Zero mortality of the fishes with no significant difference in the overall body mass with the two dietary supplements strongly suggests that algal biomass could supplement the requisite nutrients for their metabolic activities. This preliminary investigation helps in exploring algal biomass as a potential alternative feed additive in the aquaculture industry.     

Effect of diet and light regime on growth and survival of African catfish (Clarias gariepinus) larvae and early juveniles

Growth of larval sharptooth catfish Clarias gariepinus fed live Artemia nauplii , a specially prepared dry feed (MN-3), a commercial dry salmon starter feed (Silver Cup 3600), or a combination of 50% live Artemia and 50% MN-3, under conditions of either light or dark for 21 days was studied. For all diets, fish reared in darkened tanks were significantly larger than those in illuminated tanks from day 8 onwards. Fish fed a combination of live Artemia plus MN-3 grew significantly more quickly than those fed either live Artemia or MN-3 only. On day 21 of the experiment, average weight of fish fed the combined diet was 649 ± 30 mg (mean ± SEM ) in darkened tanks and 445 ± 16 mg in illuminated tanks, while those fed Artemia alone were 242 ± 9 and 198 ± 13 mg (dark and light, respectively) and fish fed MN-3 only were intermediate at 377 ± 20 and 267 ± 16 mg (dark and light, respectively). Catfish fed the salmon starter initially grew slowly, but after day 11 grew more quickly than the other groups. Mortalities were highest for fish fed salmon feed.
Permanent darkness enhances the growth of C. gariepinus larvae during and after metamorphosis. While dry diets promoted higher growth rate than live Artemia nauplii alone, a combination of the two resulted in the fastest growth.     

Effects of dietary starch and energy levels on maximum feed intake, growth and metabolism of Nile tilapia, Oreochromis niloticus

The aim of this study was to gain insight into how Nile tilapia (Oreochromis niloticus) regulate feed and energy intake in response to diets low and high in starch and cellulose. It was hypothesized that high-starch diets would reduce feed intake due to the effect of high blood glucose level, and that stomach volume may limit feed intake of fish fed diets low in energy. Four experimental diets, low starch–no cellulose inclusion, high starch–no cellulose inclusion, low starch–with cellulose inclusion, and high starch–with cellulose inclusion, were formulated. The high-starch diets and diets with cellulose inclusion were 17.5% more energy-diluted than the low-starch diets and diets without cellulose inclusion, respectively. Male tilapia were fed to apparent satiation for six weeks. Feed and digestible energy intake of fish fed diets with cellulose inclusion increased and decreased by 8.3% and 5.5%, respectively, compared to fish fed diets without cellulose inclusion. This suggests the role of stomach volume in restricting feed consumption. Fish fed high-starch diets achieved only 0.5% more feed intake and 13.9% less digestible energy intake than fish fed low-starch diets. The lower increase in feed intake and higher decrease in digestible energy intake of fish fed high-starch diets than of fish fed diets with cellulose inclusion suggests that high blood glucose suppresses feed intake in Nile tilapia. An alternative explanation for the differences in feed and digestible energy intake of fish fed different diets was based on the fact that heat production was not influenced by starch nor cellulose-inclusion levels. Thus, under satiation feeding, oxygen uptake capacity may determine feed and digestible energy intake in fish rather than blood glucose or stomach volume.     

Feeding and gut evacuation of cultured juvenile spiny lobsters, Jasus edwardsii

Low feed consumption has been suggested as a major impediment for the development of effective formulated diets for spiny lobsters. To seek an explanation for the low feed consumption, this study compared the feed consumption, appetite revival, foregut evacuation and fecal production of different sizes of spiny lobster Jasus edwardsii juveniles fed a fresh natural diet (i.e. mussel flesh) and a dry formulated diet. In addition, the effect of feeding frequency was determined by feeding juvenile lobsters the same ration of formulated diet at different time intervals. i.e., same ration delivered 3 week^− 1, 1 day^− 1, 2 day^− 1, 5 day^− 1 and 5 night^− 1. Lobster (10–15 g) growth and feed consumption (1.15% BW day^− 1) was maximized when receiving a single ration daily of the formulated diet. A slow appetite revival (AR > 18 h) on the formulated diet was consistent with the negative effect of increasing feeding frequency on growth and consumption. In addition, there appeared to be no major advantage in dry matter intake by providing the nutrient dense dry formulated diet to Jasus edwardsii. Lobsters fed fresh mussel flesh (79.8% moisture) consumed similar levels of dry matter as those lobsters fed the dry formulated feed (7.3% moisture). This appears to be due to high moisture gain and expansion of the dry feed in the lobster foregut. Foregut evacuation lasted 10 h for the two diets but a delay in initial foregut evacuation and processing of the formulated diet was evident, and may have negatively affected feed consumption, appetite revival and dry matter digestibility (61.2%) of the dry formulated diet compared to the mussel flesh diet (89.2%). Appetite revival on mussel flesh was almost complete by 12 h after a satiation ration and was governed primarily by the rate of foregut evacuation. Differences in the timing of foregut evacuation and fecal production between the two diets suggested that a greater proportion of the formulated diet entered the midgut directly.The results indicate that J. edwardsii cannot achieve high levels of feed consumption on formulated diets because gut throughput is reduced due to a small foregut capacity, expansion of the feed post-ingestion, lengthy foregut filling time (1–2 h) and clearance time (10 h), combined with slow gut throughput time (34–42 h) and appetite revival (> 18 h). A slow appetite revival and difficulties in processing and digestion of formulated diets appear as major issues to be resolved to improve the performance of formulated diets required for the commercial aquaculture of J. edwardsii and possibly other spiny lobsters.     

Protein and Energy Levels for Maximum Growth, Diet Utilization, Yield of Edible Flesh and Protein Sparing of Hybrid Clarias Catfish (Clarias macrocephalus×Clarias gariepinus)

Abstract— Two feeding trials were performed to determine dietary protein and energy levels for maximum growth, diet utilization, yield of edible flesh and protein sparing of hybrid Clarias catfish ( Clanas macrocephalus × Clarias gariepinus ). A 3 × 3 factorial design was employed for experiment 1 in which nine diets containing either 20, 30 or 40% protein and 275, 300 or 325-kcal digestible energy/100 g were used. The follow-up experiment 2 was a 3 × 2 factorial in which three protein levels (30, 35 and 40%) and two digestible energy levels (275 and 325 kcal/100 g) were tested. Dietary ingredients used in both studies were similar but the ratios of energy provided by dextrin and lard were 11.3/1.0 and 3.8/1.0 for experiments 1 and 2, respectively. Each of the experimental diets was fed to apparent satiation twice daily to three aquaria of fish (15 fish/aquaria) with average weight of 4.0 and 2.0 g for experiment 1 and 2, respectively, for 8 wk. Performance of fish in experiment 1 was mainly influenced by dietary protein rather than by energy levels. Maximum growth and diet utilization were attained at dietary protein and energy levels of 40% and 275 kcal/100 g, respectively. Energy levels did not spare dietary protein in experiment 1. In experiment 2, growth, diet utilization, and yield of edible flesh of fish were influenced by protein and energy levels. Furthermore, the protein sparing effect was observed in experiment 2. Best performance and protein sparing were found at 35% protein and 325-kcal digestible energy/100 g. The studies showed that dietary protein and energy requirement for hybrid Clarias catfish are affected by carbohydrate to lipid ratio. Fish utilize dietary energy with a dextrin to lard ratio of 3.8/1.0 more efficiently than that with a ratio of 11.3/1.0. Therefore, dietary protein and energy for best performance and protein sparing of hybrid Clarias catfish reported for experiment 2 were more appropriate.     

Induced Spawning of the African Catfish Clarias gariepinus Using Non-Piscine Pituitary Extracts

Acetone-dried hypophyses from the common toad and bullfrog administered intramuscularly was an effective inducing agent for spawning the African catfish Clarias gariepinus held in cisterns. A dosage schedule of 4–6 mg dry gland/kg female catfish applied in two installments (equal doses) is recommended. Toad and frog hypophyses were as good as or better than human chorionic gonadotropin or homoplastic injection to induce spawning of C. gariepinus under ambient temperature conditions (28–30 C).