Food and feeding habits of Tilapia zilli (Pisces: Cichlidae) in Ondo State University fish farm

The food and feeding habits of Tilapia zillii in the fish farm of Ondo State University, Akungba - Akoko, Nigeria, were studied by gut analysis. Examinations of 150 specimens showed that Nymphea formed the main bulk of food consumed. Spirogyra, Pithophora and Compsopogon occurred frequently while Pistia detritus and plant remains featured less frequently. Variation in the frequency of occurrence of the various food items was observed among the various sizes of samples. The samples within the middle - size group fed on both higher plant and filamentous algae while the young and higher fish consumed exclusively filamentous algae. On the basis of food items found in the gut, Tilapia zillii was classified as primary consumers

The distribution and feeding habits of a cichlid fish Oreochromis niloticus (Linnaeus) in Opa Reservoir, Ile-Ife

The distribution of Oreochromis niloticus was studied in Opa reservoir (Nigeria) using a graded set of gillnets while the food and feeding habits were studied using a castnet to collect the fish samples. About 90% of the fish specimens were caught near the reservoir bottom while about 69% of the specimens were caught within the inshore area of the reservoir. The species fed mainly on detritus, algae and higher plants. Feeding rhythm in O. niloticus started around 6.00 a.m. and reached a peak by 3.00 p.m. but then declined gradually until 6.00 p.m. These results can be utilized for the proper management of the fish species in the reservoir

Some observations on the absence of bacteria from acid waters in northwest England

This brief report concentrates on the effect of low pH on the initial stages of decomposition and the conditioning of incoming particulate carbon or detritus by microbes, particularly certain genera of filamentous bacteria. Although many previous reports have concentrated on bacterial decomposition processes, little attention has been given to the composition of the bacterial community and the role of its component parts, particularly in nutrient-poor waters which are provided with sources of organic carbon and reducing power in the form of poor quality detritus.

On the feeding of freshwater ostracods. [Translation of: Zoologicheskij zhurnal, 27(2), 1948, 125-136]

The present work appertains to a series of investigations in the field of trophodynamics of water bodies conducted by the department of hydrobiology ”Mosrybvtuza” under the leadership of Prof. Director N.S. Gaevska. Usually with quantitative collections of benthos ostracoda are hardly taken account of. But with the employment of special methods it is possible to be convinced that they are encountered in massive numbers. The role of ostracods in the nutrition of fish is recognised as important by many authors. On the question of the feeding of ostracods, in the literature there are only the fragmentary indications about the occurrence in the gut of ostracods of algae (diatoms, desmids) and detritus. The study of the feeding of ostracods was conducted both by the method of dissecting the guts of ostracods taken from natural waters, and by the method of feeding ostracods under laboratory conditions with a variety of food objects. Moreover, with a view to revision of obtained quantitative data, for determination of food requirements of ostracods the respiration method was applied.

On the nutrition of Polyphemus pediculus (L.). [Translation from: Trudy Instituta Biologii Vnutrennykh Vodnany 12(15) 170-174, 1966.]

Many sides of the biology of Polyphemus pediculus are adequately studied at the present time. Most complicated is the question of its feeding. Dissection does not give an idea of the composition of the food, since Polyphemus strongly grinds its food with its mandibles. For clarification of the composition of the food of Polyphemus pediculus, the authors carried out in July and August 1962 a series of experiments with the application of radio-carbon methods in order to judge the degree of utilization of one or other foods by the quantity of C14, accumulated in the body of the crustacean after feeding. Particular attention in these experiments was given to the question of the possibility of the utilization by polyphemus of plant food - bacteria, algae and detritus.

Ecologia de Astyanax taeniatus na Bacia do Rio Mato Grosso, Saquarema - RJ: Dieta, uso do micro-hábitat e uma breve análise comportamental

Neste trabalho tivemos como objetivo caracterizar a dieta, uso do habitat e padrões comportamentais de Astyanax taeniatus da bacia do Rio Mato Grosso, que encontra-se na porção leste do Estado do Rio de Janeiro (22 52 S; 42 40 W e 22 53 S; 42 34 W). Para a análise da dieta, os exemplares foram coletados bimestralmente entre março de 2006 e janeiro de 2007 em três localidades que diferiram pelas variáveis físicas. As observações de uso dos recursos do habitat foram realizadas por observação subaquática, na posição focal dos exemplares avistados, enquanto a quantificação da disponibilidade foi realizada em 50 quadrats de 20x20cm (400cm2) ao longo dos mesmos 50m onde foi realizada a observação sub-aquática. A análise do conteúdo estomacal de 651 exemplares foi realizada sob microscópio estereoscópico de acordo com métodos qualitativos e quantitativos (Freqüência de Ocorrência e Volumétrica). A participação relativa de cada item registrado nos estômagos em relação à totalidade da dieta foi analisada através do Índice Alimentar (IAi). Para verificar possíveis diferenças entre as proporções dos itens de origem animal e vegetal, autóctone e alóctone, os valores proporcionais foram testados pelo 2 de contingência. A partir dos dados de comprimento padrão e comprimento do intestino, foi calculado o valor do quociente intestinal. Os itens de origem vegetal tiveram maior contribuição na dieta da espécie para as localidades com maior altitude, enquanto os itens animais tiveram maior contribuição na localidade baixa. A diferença na contribuição dos itens de origem autóctone e alóctone também foi significativa. Na dieta de jovens e adultos, houve diferença significativa na contribuição de itens de origem vegetal e animal somente na localidade mais alta, onde os adultos consumiram maior quantidade de matéria vegetal. Os valores médios de quociente intestinal em jovens e adultos foram significativamente diferentes nas localidades de maior altitude, com valores maiores para indivíduos adultos. Observamos 52% dos indivíduos em profundidades entre 30 e 45 cm, 72% em áreas de rápido, 72% em velocidades entre 0 e 0,5km/h, 66% encontravam-se distantes da margem entre 40 e 120 cm, 37,6% em substrato do tipo areia e 34,4% em substrato do tipo pedra. De todos os padrões comportamentais observados, aquele que mais se destacou foi o forrageamento, onde 70,91% dos indivíduos estavam forrageando no meio da coluna dágua. Os resultados da dieta reforçam a idéia de as espécies de Astyanax têm hábito alimentar onívoro e oportunista, onde a espécie alimentou-se dos recursos disponíveis no ambiente evidenciando sua alta plasticidade alimentar ao longo do riacho. Espécies do gênero Astyanax são consideradas generalistas em relação ao uso do habitat e altamente ativas, corroborando com os resultados do presente estudo.

The role of infusoria and bacteria as food for Cyclopoida in Rybinsk Reservoir [Translation from: Trudy Instituta Biologii Vnutrennykh Vodnany 22(25), 37-42, 1971]

Despite the fact that it is a long time sinc e the methods of collection and quantitative estimatio n of protozoa were worked out data on the abundance of these animals in freshwaters are not very numerous. Nevertheless, Infusoria and Rhizopoda at high densities are widespread in the water and sediments of lakes and reservoirs. In order to find ou t the importance of infusoria as a food source for cyclopoids we carried out experimental investigations using C14. For this three species of cyclopoids, widely distributed in open regions of Rybinsk reservoir were selected: Cyclops vicinus, Mesocyclops oithonoides and Kesocyclops leuckarti. The data presented give evidence that the species investigated are able as predators to consume infusorian plankton arid bacteria in the form of flocs or small clumps of detritus.

Ecological study of the River Lambourn. Report for the period October 1973 to September 1977

The investigations described in this report were carried out to fulfill three distinct but interrelated objectives. In 1973 the Thames Conservancy were making plans for a second stage of their groundwater scheme which would take water from the chalk aquifers in the valley of the Kennet and they wanted basic information on the ecological state of this river and its upper tributaries. Little appeared to be known about limestone streams and a preliminary study of one of the streams in this area was desirable as a basis for planning more detailed studies if these were needed later. At a progress meeting held in March 1976 the problems and opportunities presented by the developing drought conditions were considered. It was concluded that the ecological effects of the exceptionally low natural flows should be studied and that it would be important to assess the ecological impact of the groundwater scheme if it was brought into operation that year. This could only be done on the Lambourn and the Winterbourne and it was decided that considerable effort should be diverted there for this purpose and that the field observations should be extended to cover any recovery period after the end of the drought. To make this possible it was agreed that the studies of invertebrates and detritus on the Kennet should be reduced considerably and that the proposed study of the limestone stream should be abandoned. The revised objectives were as follows: A detailed ecological study of several sites on the Kennet and its tributaries above Kintbury, extending over at least two years and involving observations on wate r weeds , invertebrates, fish, detritus and the trophic relationships within the river community. Quantitativ e and qualitative sampling of water weeds and invertebrates during one year at a number of sites on several chalk streams to determine whether the patterns and relationships found in the Lambourn are also found at the other sites. Observations on the Lambourn at Bagnor were to continue for most of the period to look for long-term fluctuations and to enable these sites to act as controls with which the other sites could be compared. Further detailed studies on the Lambourn and the Winterbourne to assess the impact of low flows, trial pumping and the operation of the groundwater scheme.

Fish bioecology in relation to sediments in the Mekong and in tropical rivers

Sediments are an essential component of rivers and of their biological functioning. In addition to their influence on river geomorphology (maintenance of river forms and habitats such as pools and sand bars), sediments also include nutrients, detritus and organic debris of various sizes which interact with the river’s different life forms, including fish. The interaction between sediments and aquatic organisms, directly or indirectly through the effects of sediments on physical habitats, unquestionably influences the biodiversity and productivity of a river. The current report reviews the interactions between sediments and fish in tropical rivers and in the Mekong, and focuses more specifically on a reduction of sediment loads following dam const

The South China Sea: analyzing fisheries catch data in an ecosystem context

The South China Sea is an important fishing area with an annual harvest of some 5 million tonnes, or 10% of the catches jointly taken by the developing nations of the world. Details are given of a model of the area describing fisheries catches and biological interactions. The area, viewed as a large marine ecosystem, was divided into 10 subsystems; each subsystem was then linked with adjacent subsystems by predatory links, and detritus flows. An analysis was then made of catch statistics for each of the subsystems. It is believed that if all systems could be harvested at around the highest efficiency, an additional 5-6 million tonnes could be taken annually from the South China Sea; however, more refined analyses are needed to further investigate these possibilities. If linked with careful studies of the economic and human aspects of fishing, such analyses will provide guidelines for integrated fisheries management advice.

Food and feeding habits of Synodontis nigrita from the Osun River, SW Nigeria

An investigation was conducted into the food and feeding habits of Synodontis nigrita from the Osun River near Epe, Lagos, Nigeria. The food items in the stomach of the S. nigrita covered a wide spectrum, ranging from various types of plankton to invertebrates and plants. A seasonal variation was also noted in the stomach contents of S. nigrita over the period of investigation. The predominant food items found in the stomach were Polycystis spp., Closterium spp., Oedogonium spp., plant tissues, insect parts and detritus. This suggests that S. nigrita is an omnivore.

Diet composition and daily ration estimates of selected trawl-caught fishes in San Miguel Bay, Philippines

The diet composition of fish caught in San Miguel Bay, Philippines, in April and May 1993 was studied. The diets of tiger-tooth croaker (Otolithes ruber), commerson's anchovy (Stolephorus commersonii); and the Indian anchovy (Stolephorus indicus) consisted mainly of zooplankton, primarily crustaceans. The stomach content of orangefin ponyfish (Leiognathus bindus) was found to consist mostly of detritus and unidentified materials. Daily rations estimated were: 1.90 g day super(1) for O. ruber of 17.3 g mean body weight (BW), 0.078 g day super(1) for S. commersonii) of 3.8 g mean BW, 0.062 g day super(1) for S. indicus of 3.9 g mean BW and 0.56 g day super(1) for L. bindus of 7.7 g mean BW.

Biology and feeding behavior of Orbinia johnsoni

Orbinia johnsoni were studied from a small sandy beach near Mussel Pt., Pacific Grove, California, where they are most abundant at low tide levels in fine sand. They were found to have a mean length of 190 mm. The orbiniids were found with their guts the fullest during incoming to high tides. It is plausible that this is when they are feeding. It takes about 3 to 3.5 hours for food to travel through the length fo the gut. The orbiniids eat 93 percent sand and seven percent organic detritus. Special note should be taken that some food selectivity appears to be involved and that high percentages of organic matter in the feces are found in worms collected during low, outgoing tides. Evidence suggests that the worms are bottom feeders, not coming to the surface to feed.

Oyster mushroom waste as manure in fish culture: a preliminary study

In an attempt to recycle the waste substrates of the oyster-mushroom crop, tanks were stocked with seed of Indian major carp Cirrhinus mrigala at the rate of 600,000/ha and waste substrate was applied at weekly interval at 0, 50, 100, 150, 200 and 250 g/tank. Oyster mushroom waste not only provided highly nutritive colonised detritus to the fish as direct feed, but also produced rich plankton in the tank. In waste treated tanks, production was better than in the control in 150, 200 and 250 g/tank treatment suggesting the possibility of fish-oyster mushroom integration.

East African Fisheries Research Organization Annual Report 1952

Several important advances have been made in our knowledge both regarding the factors which determine fertility in tropical lakes and the fish that live in them. As a result of our investigations a new theory has been put forward regarding the part played by animals in the bionomics of a lake; this theory, stated somewhat baldly, is that within certain limits the greater the number of animals in a shallow tropical lake, the greater becomes its potential fertility, and therefore the greater the number of animals it can support. The theory arises as a logical conclusion, once we accept the fact that the rate of production in such a lake is determined by the rate at which organic matter is decomposed. Bottom deposits which consist mainly of vegetable matter decompose slowly, whereas deposits which contain a high proportion of matter of animal origin decompose more rapidly. Thus the more animals in a lake, particularly animals which feed on plant material, the faster the biological cycle can proceed and the greater the density of animals it can support. This new concept will have a very profound influence on our ideas concerning the consequences of overfishing tropical waters. It also shows that efforts must be made to encourage and protect all herbivorous and detritus feeding animals, whether they be copepods, fish, or hippopotami, and whether they are of immediate economic importance or not.