On a restricted food supply of Tubifex tubifex (2h/day) the fish consumed only 69.5 mg dry food/g live fish/day and grew only to 25.6 mg live body weight by the 30th day of it's age, while those fed ad libitum consumed 94.7 mg/g/day and attained a body weight of 125.9 mg live weight by the 30th day. Conversion efficiency (K1) averaged to 8.3% in the former and 14.1% in the latter series, throughout the 30 day experimental period. Feeding rate of the test series fed individually and at ad libitum, decreased from 780 mg dry food/g dry fish/day for a fish weighing 4 mg dry weight to 180 mg/g/ day for one weighing 41 mg, exhibiting a log-log relationship to the body weight (Y = 2.20140-0.5639 X). Growth rate also decreased as a log-log function with increasing body weight (Y = 1.2309-0.4384 X). © 1977 Dr. W. Junk b.v. Publishers

Ravichandra Reddy, S.

Shakuntala, K.

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Hydrobiologia vol. 55, I, pag. 65-69, I977INFLUENCE OF BODY WEIGHT/AGE ON THE FOOD INTAKE, GROWTH AND CONVERSION EFFICIENCYOF GAMBUSIA AFFINISKATRE SHAKUNTALA & S. RAVICHANDRA REDDYDepartment of Zoology, Bangalore University, Bangalore 560 ooI, South India.Received October 7, 1976Keywords: body weight, age, food conversion in fish.AbstractOn a restricted food supply of Tubifex tubifex (2 h/day) the fishconsumed only 69.5 mg dry food/g live fish/day and grew onlyto 25.6 mg live body weight by the 30th day of it's age, while thosefed ad libitum consumed 94.7 mg/g/day and attained a bodyweight of 125.9 mg live weight by the 30th day. Conversion effi-ciency (Kl) averaged to 8.3% in theformerand 14.% inthelatterseries, throughout the 3o day experimental period.Feeding rate of the test series fed individually and at adlibitum,decreased from 780 mg dry food/g dry fish/day for a fish weigh-ing 4 mg dry weight to 8o mg/g/day for one weighing 41 mg,exhibiting a log-log relationship to the body weight (Y = 2.2014-0.5639 X). Growth rate also decreased as a log-log function withincreasing body weight (Y = 1.2309-0.4384 X).IntroductionExperimental determinations of food intake, growth andconversion efficiency are known to offer important clueswith regard to the ecological success of any organism(Kinne, 197I). These sequential parameters may be af-fected by environmental and/or endogenous factors(Pandian, I975) and the endogenous factors like bodyweight/age are known to modify the conversion efficiencyof fish (Gerking, 1952, I97I; Staples & Nomura, I976;Gerald, 1976). As a successful biological agent of mossquito control, the larvivorous fish Gambusia affinis hasbeen repeatedly introduced in various types of freshwaterhabitats (Gerberich & Liard, 966), where the fish hassurvived well even under adverse environmental condi-tions (Goodyear et al., 1972; Maglio & Rosen, I969). Thepresent paper describes the influence of body weight/ageDr. W. Junk b. v. Publishers - The Hague, The Netherlandson the food intake, growth and conversion efficiency ofG. affinis.Material and methodsGestating females of Gambusia affinis were collectedfrom a local fish farm and reared individually in batteryjars containing aerated freshwater. To minimise thegenetic variation, the 60 to 8o young ones born of a singlegestating female were used for each experimental series.Test individuals of G. affinis were fed on restricted (2 h/day) or unrestricted (ad libitum) diet of the oligocheateworms Tubifex tubifex from the first day of their birth.Sex differentiation in G. affinis occurs by 30 days of ageand involves disparity in the food intake and growth be-tween the sexes (see Love, 1970; Katre, 1976). Hence,feeding experiments were discontinued after 30 days.During the thirty days experiment, at selected intervals,the levels of the following parameters were estimated:Food intake was determined by subtracting the dryweight of uneaten food from the dry weight of daily foodprovided and expressed as mg dry food eaten/fish/day;feeding rate was calculated as mg dry food consumed/glive fish/day; growth as the gain in mg dry weight/fish/day and conversion efficiency (K,) as a percentage of foodconsumed.ResultsOn a restricted diet (2 h/day) food intake increased fromo.9 mg/day for an individual weighing I .o mg on the 9thday of it's age to 1.8 mg/day for a fish weighing 26.0 mg65Table 1. Gambusia affinis: Effects of body weight and age on food intake, growth and conversion efficiency. Each value representsthe average performance of 10 individuals reared on a restricted supply (2 h/day) of Tubifex tubifex.on the 3oth day (Table ). The corresponding values forgrowth were o.o8 and 0.13 mg/day. On the other handconversion efficiency remained more or less constant atabout 8.3% throughout the 30 day experiment. This con-version efficiency showed a slight decrease to 7.2% on the3oth day and might have decreased further beyond thisage/body weight (Raghuraman, I972).Food intake is known to be dependent on the mode ofpresentation of food and ideally the fish should be pro-vided with unlimited opportunity to feed (Brett, 197I).When the food supply of Gambusia affinis was thus un-restricted (ad libitum), the daily food intake showed anincrease from 3.3 mg on the 9th day (20.I mg bodyweight) to 7.1 mg on the 3oth day (125.9 mg body weight;Table 2); daily growth increased from 0.48 to 0.95 mg inthe corresponding period. Conversion efficiency howeverwas apparently constant (I 4. i%) but was markedly higherthan when the food was restricted (Table 1). It is evidentfrom Tables I and 2 that at any interval of age of G. affi-nis, growth depends on the level of food intake, and higherconversion efficiency is exhibited by the fish when thefood supply is unlimited. Average feeding rate was alsohigher when there was unlimited food supply (94.7 mg/gfish/ day) than when it was limited to 2 h/day )70.5 mg/gfish/day). This indicates that growth and conversionefficiency are dependent on food intake.DiscussionThe IBP scheme of energy balance (Petrusewicz & Mac-fadyen, I970) for a fish may be represented by the fol-lowing equation:C=P+R+F+UTable 2. Gambusia affinis: Effects of body weight and age on food intake, growth and conversion efficiency. Each value representsthe average performance of 10 individuals reared on an ad libitum diet of Tubifex tubifex.Age of Live body Food intake Feeding rate Growth Conversionfish weight of fish (mg dry food/ (mg dry food/g (gain in mg dry efficiency(day) (mg) fish/day) le fish/day) weight/fish/day) (K,) (%)9 20.1 3.28 163.2 0.48 14.4± 4.35 ± 0.05 ± 12.48 ± 0.056 · 0.8515 37.7 4.50 106.1 0.64 14.2± 5.60 ± 0.07 ± 11.57 ± 0.090 ± 0.7622 98.9 5.25 53.1 0.76 14.3± 8.20 ± 0.22 ± 3.98 ± 0.080 ± 0.9430 125.9 7.10 56.3 0.95 13.3± 11.36 ± 0.45 4.32 ± 0.098 ± 0.5066Age of Live body Food intake Feeding rate Growth Conversionfish weight of fish (mg dry food/ (mg dry food/g (gain in mg dry efficiency(day) (mg) fish/day) live fish/day) weight/fish/day) (K,) (%)9 11.3 0.87 79.5 0.08 8.69± 3.25 ± 0.08 ± 4.32 ± 0.007 ± 0.4615 17.3 1.12 64.7 0.09 8.30± 0.87 ± 0.15 ± 2.82 ± 0.003 ± 0.5922 18.8 1.06 68.4 0.09 8.77± 0.82 ± 0.05 ± 2.44 ± 0.003 i 0.8130 25.6 1.78 69.5 0.13 7.24± 5.25 ± 0.32 + 3.42 + 0.050 ± 0.50where C is the enrgy (food) consumed, P is the growth, Rthe energy loss as heat due to metabolism (estimatedfrom oxygen uptake), F the faeces and U the urine ex-creted by the fish. Large number of earlier publicationshave established the fact that in fishes, absorption effi-ciency, which has a bearing on the F, does not signifi-IwmLU-Ow3-zwa-cantly vary as a function of body weight (Gerking, 1952;Pandian, 1967a), quantity of food (Gerking, 1955; Davies,1963; Pandian, I967c), quality of food (Pandian, 967b)and temperature (Menzel, 1960; Hari Sethi, 1970). There-fore any factor that alters either the C, the P and/or the R,will necessarily influence the one which is not modified.DRY BODY WEIGHT(ms)Fig. . Gambusia affinis: Daily ration and growth (expressed as percentages of dry body weights) as functions of bodyweight of fish fed on Tubifex tubifex, under optimum laboratory conditions (fish reared individually in freshwater at25 ± I1C and fed ad libitum).67)OThe C of Gambusia affinis of different body weights fedat optimum laboratory conditions (individual values ob-tained from the mean values given in Table 2), decreasedas a log-log function of the dry body weight from 78%body weight for the 4 mg G. affinis to 8% body weightfor a 4I mg fish (Fig. I). A similar log-log relationship hasalso been reported for Onchorhynchus nerka (Brett,197I), in which the decrease is from 17% body weight fora 4 g fish to 4.3% body weight for a 216 g fish. The valuesobtained in the present study cannot be compared withthose of Brett (1971) for 0. nerka or Davis and Warren(1968) for 0. tshawytscha due to the large differences inthe body weights of the test individuals used in the ex-periments. However, the value of the C obtained for a 16mg live G. affinis (78% body weight) is comparable to thatobtained by Krivobok (1953) for the young wild carps(Cyprinus carpio) of 15 mg live weight (54% body weight).On the whole, the C values obtained for G. affinis in thepresent study are rather high when compared to thoseobtained by Karzinkin (1952) for either the young inconnu(Stendus sp.) or the young sturgeon (Acipenser guilden-stadti) of the comparable body weights (see Winberg,I960). Winberg (960) computed that for a fish weighingioo mg live weight, the C would be 8 or 35% body weight,for fish with a P (K1) efficiency of 6 or 48 respectively. Acorresponding sized G. affinis where the K1 during thepresent experiment never exceeded I4.4% (Table, 2),yielded the C value of 31.40% body weight per day (note:The water content of Tubifex worms used during thepresent experiment averaged to 83.6% of the live weightof the worms). Based on the oxygen consumption values,Winberg (960; 96I) reported that in viviparous Cypri-nodont fishes which are small in size, the R is low anddecreases more than usual with increase in weight of thebody. The high values obtained for the C in the cyprino-dont fish G. affinis of body weights ranging from 4 to 8mg dry weights suggest that the R may still be high. TheC however, decreases with increasing body weights at therate of 1.8% body weight for every 10 mg increase in thedry body weight of the fish; although, the P value de-creases as a log-log function per se (Fig. ) the proportio-nate decrease in the R is not as high as in C, so that aftera particular body weight (maximum final weight of thespecies) is reached, growth of fish ceases (see Parker &Larkin, 1959; Brett, 1970).Pandian ( 967a) has considered that body weight of thefish approximately represents the age of the fish. Theresults obtained for Gambusia affinis lead us to concludethat these two parameters need not always be representingeach other. For instance, an individual of 20 mg bodyweight, on a restricted food supply exhibited a feeding rateof only 68 mg/ g fish/ day at the age of 22 days, but a fish ofthe same body weight on unrestricted food supplyexhibited a higher feeding rate of 63 mg/g fish/day bythe age of 9 days. Similarly, a 15 day old G. affinis on arestricted food supply and a lower feeding rate of 65mg/g/day weighed only 17 mg while a fish of the sameage, on an unrestricted food supply, by virtue of its highfeeding rate (106 mg/g/day), weighed 38 mg (Tables I &2). However, when the fish was exposed to the same set ofenvironmental conditions, especially the availability offood, there was some correlation between the body weightand the age as indicated by the minor deviations from themean values given in the tables. It may therefore besuggested that, while conducting laboratory experimentson fish, especially during its growth phase, both bodyweight as well as age of the individuals must be consideredrather than any one of these parameters only or else theindividuals must be collected from a single population,living in the same set of environmental conditions.ReferencesBrett, J. R. 1970. Fish-The energy cost of living. In: Marineaquaculture pp. 37-52. Ed. W. J. Mc Neil, Oregon stateUniversity press.Brett, J. R. I97I. Satiation time, appetite and maximum foodintake of sockeye salmon (Oncorhynchus nerka). J. Fish. Res.Bd. Canada. 28, 409-415.Davis, G. E. & Warren, C. E. 1968. Estimation of food consump-tion rates. In: IBP methods of assessment of fish production infreshwater. Ed. W. E. Ricker, Oxford, Blackwell Scientificpublications, pp. 204-225.Davies, P. M. C. 1963. Food input and energy extraction efficien-cy in Carassius auratus. Nature, 198 (4881), 707.Gerald, V. M. I976. The effect of size on the consumption, ab-sorption and conversion of food in Ophiocephalus punctatusBloch. Hydrobiologia, 49 (I), 66-77.Gerberich, J. B. & Laird, M. 1966. An annotated bibliography ofpapers related to the control of mosquitoes by the use of fish.WHO/ Mal/66-562.Gerking, S. D. 1952. The protein metabolism of the sunfishes ofdifferent ages. Physiol. Zool., 25, 358-372.Gerking, S. D. 1955. Influence of rate of feeding on bodycompo-sition and protein metabolism of blue gill sunfish. Physiol.Zool., 28, 267-282.Gerking, S. D. 1971. Influence of rate of feeding and body weighton protein metabolism of bluegill sunfish. Physiol. Zool., 44,9-I9.Goodyear, C. P., Boyd, C. E. & Beyers, R. J. 1972. Relationshipsbetween primary productivity and mosquitofish (Gambusiaaffinis) production in large microcosms. Limnol. Oceanogr.,17, 445-450.68Hari Sethi, S. 1970. Temperature and bioenergetics of Cichla-soma bimaculatus. Ph. D. Thesis, Oregon University.Karzinkin, G. S. I952. Foundations of the biological productivityof waters. Pishchepromizdat, Moscow.Katre, S. 1976. Effect of feeding level on the rate and efficiency offood conversion in the cyprinodont fish Gambusia affinis (Inpress).Kinne, O. 960. Growth, food intake and food conversion in aeuryplastic fish exposed to different temperatures and salini-ties. Physiol. Zool., 33, 288-317.Kinne, O. 1971. Marine Ecology. Vol. I: Environmental factorspart 2. pp. 683-1244 London, Wiley Interscience.Krivobok, M. M. 953. Utilization of food by young wild carp inthe Azovo-Dolgii hatchery and rearing station. Trudy.VNIRO, 24, 102-1 i6.Love, M. R. 1970. The chemical Biology of Fishes. London, Aca-demic press. pp. 547.Maglio, V. J. & Rosen, D. E. 969. Changing preference for sub-strate colour by reproductively active mosquito-fish Gambusiaaffinis (Baird and Girard) (Poecillidae, Atheriniformes). Ame-rican Museum, Novitates. No. 2397.Menzel, D. W. 1960. Utilization of food by a Bermuda reef fish,Epinephelus guttatus J. Cons. perm. int. Explor. Mer., 25, 216-222.Pandian, T. J. I967a. Intake, digestion, absorption and conver-sion of food in the fishes Megalops cyprinoides and Ophi-cephalus striatus. Mar. Biol., , 16-32.Pandian, T. J. g967b. Transformation of food in the Megalopscyprinoides. .Influence of quality of food. Mar. Biol., I, 60-64.Pandian, T. J. 967c. Transformation of food in the fish Mega-lops cyprinoides 2. Influence of quantity of food. Mar. Biol., i,I07-I09.Pandian, T. J. 1975. Mechanisms of Heterotrophy, In: MarineEcology Vol. II, Part , Ed. by 0. Kinne. pp. 61-212, London.John Wiley and Sons.Parker, R. R. & Larkin, P. A. 1959. A concept of growth in fishes.J. Fish. Res. Bd. Canada, 6, 721-745.Petrusewicz, K. & Macfadyen, A. 1970. Productivity of terrestrialanimals. IBP Hand book No. 13, Blackwell Scientific Publica-tions Oxford, pp. 9o.Raghuraman, R. 1972. Effect of body weight on intake andconversion of food in the fish Rasbora daniconius. Curr. Sci.42 (1), 24-25.Staples, D. J. & Nomura, M. 1976. Influence of body size andfood ration on the energy budget of rainbow trout Salmogairdnerii Richardson. J. Fish. Biol. 9 (), 29-43.Winberg, G. G. 1960. Rate of metabolism and food requirementsof fishes. Fish. Res. Bd. Canada. Transl. Series. No. 194, pp.202.Winberg, G. G. 1961. New information on metabolic rate infishes. Fish. Res. Bd. Canada, Transl. Series. No. 362, pp. I I.69

Influence of body weight/age on the food intake, growth and conversion efficiency of Gambusia affinis

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Influence of body weight/age on the food intake, growth and conversion efficiency of Gambusia affinis

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