Some ecological factors of the tropical floodplain influencing the breeding and conservation of Gymnarchus niloticus (Cuvier 1829): a review

Gymnarchus niloticus is the only species of the family Gymnarchidae. It is a popular food fish in most parts of Africa where it is greatly esteemed. In some culture, it is offered as a special gift to leaders during festive seasons, while in some others it is an important part of items presented by a suitor to the parents of a girl at the time of betrothal. It can therefore be inferred that G. niloticus is not only important as food fish with economic significance, but also plays vital roles in the socio-cultural life of some African tribes. The supply of this important species still depends largely on the catch from the wild. However, based on the method of catch, it has been classified as endangered. A close examination of the ecological factors in the floodplain (where it migrates to breed), revealed strong influence on the breeding and survival of the fish. The level of rainfall determines the extent of floodplain inundation, and the abundance and survival of the flora and fauna in the area. These in turn determine the availability of breeding substrates and natural food sources for the various stages of G. niloticus. Therefore, rainfall, the flora and the fauna of the floodplain play vital roles in the breeding and survival of G. niloticus in nature. To ensure the conservation of this important species, controlled propagation strategies that draws on the influence of prevailing ecological factors in the floodplain is recommended. This will ensure conservation, and protect the economic and socio-cultural significance of G. niloticus

Identification, distribution and prevalence of ecto-parasites associated with cultured fish in Ogun State, Nigeria

Public health issues can he considered as those of direct importance to both producers and consumers of fish and include broader issues of food production, processing and delivery systems. As aquaculture assumes an expanding role in meeting consumer demands for fish and fishery products, it is natural that they meet safety and quality standards. Aquaculture is a growing industry in Nigeria and it has assumed commercial importance activity. This study was part of the project on epizootiological survey of pathogenic diseases of cultured fish species and is aimed at identifying ecto-parasite associated with cultured fish in Ogun State, Nigeria. The study which was carried out in 2012 covered fifty fish farm, spread across the three senatorial zones. Five pieces of fish were randomly picked from each farm surveyed. Participants observation and structured questionnaires were administered to fish farmers in order to gather information on source of fries, fish feeding and feed type, use of manure and its type, pond type, stocking density, pond hygiene, water source, frequency of changing water and history of diseases and mortalities of fish. Before the fish samples were collected, pond size and physicochemical water quality were assessed. Water test kits were used to measure parameters like iron, nitrate, alkalinity and ammonia. All the procedures for physicochemical water quality parameter analysis was done according to the manufacturer's instructions. Water pH was measured using a probe while dissolved oxygen and both water as well as air temperature were measured by using Hanna kit. All types of farms are included in the survey such as hatcheries, brood stock farms as well as grow out farms. The study revealed the spread of parasites across the senatorial zones. The most common encountered parasites were Trichodina sp, Gyrodactylus sp, Dactylogyrus sp and trematodes. The intensity of the parasites differed markedly