Natural Food in Fish Ponds

1. Natural Food in Fish Ponds

2. Natural Food in Fish Ponds • Different types of natural food forms a definite relationship among themselves in a pond ecosystem. • This relationship describes how energy and nutrients pass from organism to organism. • Energy is locked into food by plants (mainly phytoplankton) and then transferred to primary consumers (mainly zooplankton and bottom fauna) and ultimately consumed by fish (secondary consumers). • Thus, a food chain or web is formed within the aquatic ecosystem. • Food chain begins with a single producer organism, but a food web may involve several producers.

3. Progressive fish farmers use a number of small ponds for cultivation of natural food for fry and fingerlings of fishes. • They use natural food organisms rather than artificial ones particularly for young fish. • Therefore, question may arise how different types of natural food are developed in fish culture environment. • The answer is that natural food should be cultivated in ponds using different scientific techniques.

4. Classification of Natural Food • Natural food organisms which are used by carps, are comprised of • phytoplankton, • zooplankton, • diatoms, • some Protoza, and • Annelids • which are well adapted to freshwater environments . • In general, however, natural fish food organisms are classified into two types such as • (1) plankton and • (2) bottom fauna. • The former types are present in water as suspended condition and the latter types remain on the bottom mud.

5. Plankton :- is defined as free-floating microscopic or sub-microscopic plant and animal and possess feeble locomotory power. • Neustons :- are organisms which are related to surface water either by hanging upon the surface film (Gyronidae, Gerridae etc.) or by hanging against the lower side (insect larvae, protozoa, algae etc.). • True plankters:- belong to the euplankton and are classified as: • macro-plankton (> 3mm in size such as mysids, euphausids etc.), • micro-plankton (<3mm in size) and • nano-plankton (> 60um in diameter).

6. CONT… • On the basis of the quality, plankters can be divided into two types. • (1)phytoplankton • (2)zooplankton. • Phytoplanktons are chlorophyl-containing organisms • while zooplanktons are plankters of animal origin.

7. Furthermore, on the basis of site of occurrence, planktons are of various types such as • (a) lake plankton (or limnoplankton), • (b) running water plankton (or heoplankton), • (c) pond plankton (or heleoplankton), • (d) salt-water plankton (or helioplankton), and • (e) brackish-water plankton (or hypalmyroplankton).

8. Fluctuations of Plankton in Ponds • In any fish culture ponds, there occur qualitative and quantitative variations in plankton populations. • Some species of plankton reappear at specific periods and disappear during others. • The concentration of phytoplankton is always greater than that of zooplankton. • Moreover, the concentration of plankton in different months and seasons also varied greatly.

9. Fluctuations of plankton depend upon the • geographical and climatic conditions of a particular ecosystem and • different abiotic factors of water such as • pH • dissolved oxygen • total alkalinity • Hardness • temperature • ammonia and • nitrate nitrogen.

10. Culture of Natural Food • Addition of inorganic and organic fertilizers such as urea, ammonium sulfate, lime, oil cakes and cattle dung in freshwater ponds increase the nutrient levels which supports excessive growth and development of algal blooms and macrophytes. • Nitrogen and phosphorus are the key for the occurrence of algal blooms in ponds while calcium increases the absorption of phosphorus by phytoplankton

11. CONT… • Most species of phytoplankton such as Spirulina nordestedtii, Trachelomonas vaolvocina, T. charkoweinsis, Phromidium fragile, and Microcystis aeruginosa are found in abundance in freshwater bodies that have tendency of either light scale deposition of calcium carbonate or have a property of corrosion. • It is needless to mention that fertilization of ponds accelerated the growth and development of phytoplankton upon which zooplankton is dependent. • Zooplankton concentration is developed when pond is fertilized with organic materials particularly cowdung and poultry litter. • In fish culture ponds, Daphnia sp., Moina sp., Cyclops sp., Diaptomus sp., Brachionus sp., Filinia sp., Asplanchna sp., Mesocyclops sp. etc. of the groups Rotifera, Cladocera and Copepoda are developed.

12. if plankton populations are collected from water bodies and introduced into the culture ponds, the ponds will exhibit plankton swarms. • Zooplankton feeds on the small green algae and diatoms and also on dead animal and decaying vegetable matter. • Generally light and temperature hasten the life processes of various species of planktons. • Summer, monsoon and winter makes little difference in their concentration, except that the greatest abundance is in summer. • Pond fertilization with inorganic and organic materials is initiated the development of first trophic level (such as phytoplankton) and as a result greenish color of the water first appear. • As soon as zooplankton populations are inoculated or developed, the greenish color gradually disappears due to consumption of plant nutrients by zooplankon. • This cycle should always be maintained during fish culture operation for sustaining yield of fish biomass.

13. Natural Live food (Moina and Chaetocaros) • Taxonomic Classification: • Kingdom: Animalia • Phylum: Arthropoda • Sub-phylum: Crustacea • Class: Branchiopoda • Order: Cladocera • Sub-order: Eucladocera • Family: Moinidae • Genus: Moina • Species: Moina micrura •  The cosmopolitan Moina micrura is argued to be not a single species, but rather a cryptic species complex (Martínez-Jerónimo et al., 2007). •  Anatomy: • Approximately 0.5 mm in length, Moina micrura (Figure 1) is relatively rounded in body shape, yet possesses a relatively large, distinct head

14. Chaetoceros • Chaetoceros is probably the largest genus of marine planktonic diatoms with approximately 400 species while Diatoms are a major group of algae • Order: CentralesFamily: Chaetocerotaceae (Centric Diatoms)

15. Brachionus • About 2,500 species of rotifers have been known from global freshwater, brackish water, and seawater. Brachionus is one of the most common genera among the known 2,500 rotifer species. • The genus is important zooplankton species as a primary live food source for the early life of both marine and freshwater animal species. Body of Brachionus is covered by a distinct cuticle, bilateral symmetry and sexual dimorphism. • The body is comprised of four regions: head with corona, neck, body, and foot. • The foot is an appendage that extends from the body ventrally.

16. Mass Culture of Moina and Chaetocaros • The natural live food organisms supply minerals, micronutrients, proteins, fats, and carbohydrates resulting in healthy growth of fish fry • therefore, the culture of live food species is necessary. • Mass culture of Moina, sp. and Chaetocaros sp. can be done using organic and inorganic fertilizers. • these species can be cultured using slurry prepared with groundnut cake, single superphosphate and poultry litter or cow dung in the ratio of 2:1:4, respectively.

17. Mass Culture of Moina and Chaetocaros • Generally 10 kg of groundnut cake, 5 kg of single superphosphate and 20 g of chicken litter is mixed with 500 litres of freshwater. • This mixture is called slurry and is kept under continuous stirring to remove harmful gases developed during the process of degradation of organic manures. • The slurry is added at the rate of 4 ml per liter for the first three days. Then the application rate of slurry is reduced to 2 ml per liter per day. For continuous culture, it is necessary to replace one third of the water from the culture system with filtered freshwater.

18. Mass Culture of Brachionus • For culture of this species in the laboratory, 100 ml capacity test tubes are filled with 16 ppt of filtered brackish water and inoculated with one individual per ml. • Brachionus sp. is fed with yeast suspension at the rate 200 ml per liter once in a day and about 250 individuals per liter is obtained within four days. • These test tube cultures are used as stock cultures. • A series of 30 liter plastic jars are filled with 12 ppt filtered brackish water and inoculated with 300 individuals per liter

19. Brachionus sp. is fed with yeast suspension at the rate of 400 ml/lit. • The species will multiply until production of about 250 individuals per liter is obtained. • The stock culture is used as inoculum of mass culture using slurry at the rate of 4 ml per liter for the first three days followed by 2 ml per liter per day • After one week of inoculation, the total concentration ranges from 2.0 to 2.5 lakhs per liter. • If the species is harvested at peak densities and replaced at regular intervals, the culture can be continued up to 60 days.

20. Mass Culture of Daphnia and Cyclops • For mass culture of Daphnia spp. and Cyclops sp. freshwater is used as medium. • Inoculation of this two species is done separately at the rate of 50 individuals per liter. • After a week of inoculation, they reach peak density varying from 15,000 to 20,000 per liter. • Continuous mass culture can be maintained by harvesting and replacement at regular intervals.

21. Continuous Mass Culture of Zooplankton Nut • Fish nursery management practices for mass culture of the larvae of commercially important fishes require the provision of excessive quantities of zooplankters comprising principally rotifers, cladocerans and copepods at field levels which enhanced seed production to the extent of about 80 per cent by phased fertilization techniques. • Phased fertilization is a method of adding adequate amounts of organic manures along with phosphatic fertilizer at fixed time intervals so that zooplankton populations can be generated. • The biomass of planktonic bacteria produced due to the breakdown of organic manures, is consumed by zooplankton. • The zooplankton populations will grow with equal rate leading to mass culture.

22. Method of Culture • In the laboratory, stock culture of zooplankton is maintained in one liter beakers. • Manuring with groundnut cake solution is made every 48 hrs by introducing I ml of manuring solution adjusted to 4 ml/liter rate o the basis of studies on its solubility in freshwater. • It has been observed that 0.26 g is dissolved in 1liter of water out of 1 g of the gross oil cake. • On the basis of this information, the strength of stock solution is adjusted to 4 mg/liter so that 1 ml of this solution is enough every 48 hrs to maintain cultures in 1 liter beakers. For mass culture, a plastic pool with a capacity of 2,404 liters is set up in the field. • The pool is filled up with filtered freshwater. • Crude fertilizer solution is prepared by grinding 37 g of groundnut cake and producing the soluble part at 4mg/L rate.

23. This soluble part is used in plastic pool. • On the second day, 110 g of calcium oxide is added, thereby increasing the pH to nearly 8.2. • On the third day, the cultured zooplankton from one liter beaker is introduced into the pool. • During this first cycle the population of zooplankton is allowed to grow for total number of 15 days from the first day. • A second application rate of fertilizer solution is applied during the first cycle at the end of 15 days to boost zooplankton biomass production. • Thereafter following observation is made every day:

24. Standing Biomass By plankton net operation (made of 120 mesh cloth with a diameter of the opening ring around 27.5 cm), the total quantity of 340 litres of pool water is filtered. Before collection of zooplankton, the pool water is agitated for uniform distribution of zooplankton biomass. The standing biomass per liter of plastic pool and for the entire pool is determined. 2. Total Debit per Day: The standing biomass is collected twice or thrice per day. Net weight is determined so as to work out the total debit weight per day. By using this data, the closing balance of zooplankton biomass is determined by weight. By comparing the closing balance of pervious day and the opening balance of the following day, the zooplankton biomass added or deleted due to continuous production/declining process is determined per day. the population of zooplankton is allowed to grow for a total number of 15 days

25. it is clear that the first cycle lasted for total of 21 days. For other cycle, the duration varied from 15 to 28 days. However, the average number of days per cycle, is 22.6 days. The standing crop of zooplankton and the total debit per day increased from first cycle to the third cycle and thereafter it declined. • For a total of 113 days, nearly 798.458 g of zooplankton is able to exploit and at the end of the last day of exploitation, 32.794 g of biomass still remains in the pood. Therefore after 113 days, the total quantity of zooplankton biomass produced in a pool of 2,404 litres capacity is about 834.252 g. • The day on which the less production is observed indicates that the phase fertilizer at the standard rate should be introduced so as to start the new cycle.

26. For production of 834.252 g biomass, only 222 g of groundnut cake is used. • The decline of biomass from the fourth cycle onwards is possibly due to loss of water quality resulting from cumulative effect of metabolites. Of course, this problem can be alleviated by changing 50 per cent of water from the pool at the end of fifth cycle which will help to maintain the steady mass culture

27. Micro-nutrients and Abiotic Factors in Mass Culture • In addition to organic and inorganic fertilizers, use of some trace elements are necessary for enhancing the growth and reproduction of different species of zooplankton. • Population of Moina micrura in cement cistern of 185 ml capacity has been found to increase in freshwater treated with 0.2 and 0.4 mg of zinc sulfate per liter in combination with Farm Yard Manure (FYM) at the rate of 500 mg/liter. • Use of copper sulfate and zinc sulfate at the rates of 0.08 and 0.6 mg/liter respectively in combination with FYM or cowdung was also found to increase the average zooplankton population. • Among different trace elements, cobalt chloride, ferrous sulfate, zinc sulfate, copper sulfate and magnesium sulfate are very effective in combination with manures and fertilizers for mass culture of zooplankton.

28. It has been estimated that for successful culture of zooplankton, water temperature ranging between 21 and 28°C was found to be suitable because at this range of water temperature, growth and reproductive potential of different species of zooplankton proceeds in an unhampered manner. • Increase of pH (8.2-14.0) and total alkalinity ( 70-250 mg/L) of water were also found to be superior for production of zooplankter.

29. Bottom Fauna • Although benthic macrofauna form either predatory animals or essential food items for various commercially important species of fish, very little importance has been given on the population structure and biomass of benthic animals in fish culture ponds. • Bottom fauna is significant to understand the relationship between benthic animals and fish production and also to exploit biological productivity in fish ponds. • Generally the dynamics of benthic fauna in ponds largely depends upon the topographical conditions of a particular area, nutrient levels, abiotic factors of soil, and pollution status of ecosystem where they live temporarily or permanently.

30. Bottom Organisms • The term bottom organisms or benthos means the community of species of plants and animals which live in the bottom of a water body. • Many bottom organisms possess self movement from one place to another and hence they are responsible for increasing soil fertility and ultimately triggers the yield capacity of fish and other aquatic animals. • They form essential food items of be many commercially important species of some aquatic fauna including fish.

31. Existence • Although all ponds are heavily infested with various species of bottom organisms in varying quantity, their absence or presence principally depends upon the • physico-chemical properties of nutrient and • trace element loads in water bodies, • soil structure and • Soil texture, • seasons and • geographical areas of ponds. In ponds where fertilization and manuring programs are extensively undertaken for constant fertility, their existence is perpetual and therefore, there is excessive growth of bottom organisms. However, the above-mentioned factors accelerate the potential behavior of bottom organisms and their successful existence in soil of any ecosystem.

32. Development • Manuring and fertilization of ponds play a key role for the growth and development of bottom organisms. • Recently it has been reported that several agricultural chemicals at sublethal levels exert their synergistic influence on potential level of nutrients in soil which are essential for the growth of micro-organisms, act as metabolic activator and triggers to increase the number and growth of soil organisms. • Generally partially or completely degraded molecules of chemicals stimulate growth of different species of micro-organisms (protozoa, bacteria and fungi) in pond soil leading to their higher numbers in significant amounts.

33. Development • Several bottom organisms due to their browsing behavior in the sediments ingest contaminated micro-organisms as food which stimulates to increase their growth and other physiological activities. As a result fish food species consume such types of organisms and exhibit significant increase in fish yield. • Thus, a food web is formed in the benthic region itself of ponds among micro-organisms, bottom fauna. The relative importance of growth of bottom organisms is likely to vary according to the levels and types of nutrients in aquatic ecosystem.

34. Classification • On the basis of their habitat, the benthos has been classified as • endobenthos (boring in the solid substrate), • herpobenthos (growing through mud), • psammon (growing through sand), • haptobenthos (attached to immersed solid surface), and • rhizobenthos (rooted and extending into water). • In general, the most commonly encountered bottom organisms in fish ponds have been divided into Zoobenthos and Phytobenthos.

35. Zoobenthos • Larval and adult forms of different groups of fauna such as Oligochaeta, Insecta (Diptera, Collembola, Odonata, Coleoptera, Ephimeroptera), and Mollusca (Bivalvia, Gastropods) are considered as an important constituent in fish ponds. • The dominant forms bottom of zoobenthos include Tubifex, Lumbriculus, Pheretima, Branchiura, Dero, Chaetogaster; Aeolosoma, Mesenchytraeus, Culicoides, Chironomus, May fly nymph, Dragon fly nymph, Dytiscus, Cybister, Gyrinus, Pila, L.amellidens, Pisidium, Viviparus, Lymnaea, Melanoides, Digoniostoma, Cypris, and Eucypris.

36. Phytobenthos • In many ponds, various species of algae form a green scum over pond bottom. • Different groups of flora such as Chlorophyceae, Myxophyceae, and Bacillariophyceae comprise various species of Oedogoniuim, Oscillatoria, Botrydium, Ulothrix, Coleochaete, Closterium, Microsterias, Nostoc, Navicula, Amphora, Spirogyra and others. • As the eutrophic zone in many ponds is limited, an appreciable amount of phytoplankton sinks below and forms the food of many benthic communities. • Therefore, a magnitude of phytoplankton population could sustain a very rich in zoobenthos of ponds.

37. Management • The main aspect of bottom organisms involves their adequate management and maintenance of a high quality ecosystem for their success. Because of differences in ecological conditions among localities, the management procedure may vary greatly and therefore, these differences should be considered precisely. • It has been demonstrated many times that there is a positive correlation between bottom organisms and fish production. Generally nitrogen, phosphorus, organic matter and lime determines the productivity of fish ponds through development of bottom organisms.

38. Management • Newly constructed ponds have insignificant amount of benthic organisms than older ones due to presence of nutrients in very low amounts. • Of course, the progressive fish farmers do not consider the age of ponds during pond management program. The bottom mud should not be highly acidic because bottom organisms do not grow well at low pH and organic matter. • Therefore, liming and fertilization have more than doubled the production of benthic organisms in ponds.

39. Role of Abiotic Factors and Toxicants • A number of bottom organisms appear at specific period while other forms disappear. • The periodic appearance and disappearance of bottom organisms are controlled by • Nitrate • ammonia • Phosphate • pH • Temperature • Salinity • total alkalinity • hardness, • dissolved oxygen, • and trace elements present in water. There is significant correlations between different groups of bottom fauna and abiotic factors of soil.

40. Role of Abiotic Factors and Toxicants • During rainy season, aquatic ecosystems are contaminated with a variety of toxic chemicals generated from diverse sources such as domestic, agricultural and industrial. • Among different types of pollutant, pesticides, heavy metals and detergents are the major cause of concern for aquatic environment because of their persistency and tendency to bottom mud and organisms. • The impact of these pollutants on bottom organisms is due to the movement of toxicants or point sources which gives rise to coincidental mixtures in the ecosystem.

41. Abundance and Variations of Bottom Fauna • The productivity of benthos is closely associated with the fish production and exchange processes in the profundal zone. • Therefore, abundance and fluctuation of different species of bottom fauna in fish culture ponds are very important so far as the indicator of water quality and eutrophication are considered. • The abundance of bottom fauna is seasonal and irregular. • For example, molluscan species strongly dominated all the year round (49.3-80.5 per cent) than that of other groups of bottom fauna. Oligochaetes ranked second (9.8-31.9 per cent) followed by Insects (8.5-26.9 per cent). • However, in many lentic pond ecosystems, a different trend of the mean concentration of bottom fauna in different months is a common occurrence and their numbers also varied.

42. Seasonal abundance of various forms of bottom fauna revealed that insect populations were abundant during summer-monsoon seasons followed by oligochaetes (summer – winter) and molluscs (monsoon –winter) • Monsoon season seems to be the most important factor influencing the abundance of insect fauna • Therefore season variations must be considered so that fertilization and manuring program can be manipulated in such a way that production strategy of bottom fauna may proceed in an unhampered manner

43. Interactions Between Bottom Fauna and Nutrients • Nutrient carriers such as nitrogen, phosphorus and oil cakes are the most important compounds regulating biological productivity of water bodies, and their cycles are the basis for management of fish culture systems. • But their accumulation in excessive amounts cause deleterious effects on fish food organisms particularly bottom organism. However, optimum levels of nutrient trigger survival, growth and reproduction of algae and bacteria, which in turn, sustain populations of zooplankton and bottom organisms resulting in utilization of these organisms by different species of fish. • Although there is no clear explanation for the direct influence of chemical fertilizers and organic manures on fish growth in ponds, a partial explanation involves the relationship between nutrient load and fertilizer treatment.

44. Fertilizers exert their synergistic influence on the potential level of nutrients, which are essential for he growth of microorganism, by acting as metabolites activators that trigger the growth and reproduction of soil organisms. • Because the concentration of microorganism depends upon the amounts of nutrients in the soil, it is not unrealistic to expect fertilizers to effect the growth dynamics of soil organisms.

45. CONT… • It is possible that nutrients of fertilizers at optimum rates are absorbed or absorbed by bacteria, and hence removed from the soil by different species of bottom organisms. • Chemical fertilizers and organic manures are degraded by bacterial, and as a result, a variety of metabolites are released into the sediments and ultimately act on the biomass of bottom fauna. • The residual as well as the direct toxicity of some toxic compound (such as 2, 4-D, atrazine, simazine etc.) causes mass mortality of plankton populations, particularly in the early stages of development. • On degradation, the result is a release of nutrients for the growth of bottom organisms. • However, partially or completely degraded fertilizers in the sediments stimulate bacterial growth rates, these molecules are used in microbial cell synthesis and lead to higher numbers of bacteria.

46. CONT… • Some benthic animals ingest contaminated bacteria / algae as food from the sediment. • Fertilizers and manures also enhance the metabolic capacities of bottom organisms after entering their bodies. • The increased accumulation of nutrients following induction of various abiotic factors of the ecosystem is more likely to result from fertilizer affinity for cellular structures. • In ponds where fertilizers and maures increase the number of bacterial and algal species, the bottom fauna engulf these contaminated bacteria and as a result the concentration of bottom fauna is increased.

47. Energy Contents of Natural Food • Determination of calorie is very essential so far as the bioenergetics are considered. • Measurement of energy in fish food organisms of an ecosystem provides the reliable information of the functional nature of the communities. • A comparative estimates of energy content of some common fish food organisms have been made using wet oxidation method and bomb calorimetry and the results obtained in the latter method were only within 3 per cent higher than the former. • The highest calorific value (7.12 K cal./g) was recorded in tubificid worm while the Cypris has the minimal value 93.62 k cal/g)

48. Natural Feed Ingredients • Generally the bottom-dwelling fish have benthiophagic omnivorous feeding habits. • The main food items consumed include crustaceans, molluscs, annelids, insects, and associated detritus-based micro/ meiofauna and flora. • An important fact has come out from the survey on natural feed ingredients is that cultured freshwater fish generally feed lower on the aquatic food chain and a large variety of food organisms than their marine counterparts. • However, due to natural feeding habits of different species of freshwater fish, a wide variety of natural food items have been used by fish farmers as exogenous feed sources for their culture operations.

49. Processed Feed Ingredients • These include all plant and animal food items which have been physically processed prior to feeding either by composting, grinding, cutting, drying or by mixing with other food items into a compound diet. Although it is difficult to compare the results obtained from different experimental trials under varied agro-climatic conditions, a systematic analysis of the data is difficult to draw a definite conclusion because of the absence of definite ingredient definitions such as: • international feed number, • ingredient particle size prior to feeding or mixing, and • proximate chemical composition. • For example, the ‘shrimp meal’ has been declared proximate composition — 3.2% crude fat, 71.8% crude protein, 3.14% crude fibre, and 16.9% ash. • This cannot be nutritionally compared with ‘shrimp meal’ which has been declared proximate composition — 4.5% crude fat, 43.3% crude protein, 10.7% crude fibre, and 34.5% ash.

50. Major Processed Feed Ingredients Used as Feed for Freshwater Fish Animal by-product Earthworm meal, Fish meal, Fish silage, Trash fish, Poultry by-product meal, Blood meal, Meat meal and Feather meal Plant by-product Soyabean meal, Cotton seed meal , Mustard seed meal, Rice bran and Rice polished, Wheat meal ,Corn/Maize meal, Turnip leaves ,Lucerne/Alfalfa ,Single-cell proteins (SCP): Bacterial SCP, Algal SCP and Fungal SCP