Broodstock nutrition in Nile tilapia and its implications on reproductive efficiency

Broodstock nutrition is the most essential constituent of sustainable aquaculture production. Its impact on the reproductive performance and profitability of commercial aquaculture has been the subject of considerable research. The present paper reviews the literature available on the subject, examining the implication of Nile tilapia broodstock nutrition on parameters including maturation, fecundity, fertilization, embryo development, larval quality, and survival rate. The provision of a nutritive diet composed of essential macro- and micronutrients including proteins, lipids, carbohydrates, vitamins, minerals, and functional additives, such as prebiotics, enzymes, hormones, and probiotics, in different proportions is discussed. Special emphasis is given to literature dealing with the effects of dietary protein and lipid on vitellogenesis and ovarian maturation, fecundity, egg hatching rate, larval quality, and fry survival number. The impact of the feeding regime on reproductive performance is described

Bioflocs Technology in Freshwater Aquaculture: Variations in Carbon Sources and Carbon-to-Nitrogen Ratios

Aquaculture is one of the fastest food-producing sectors contributing half of the food fish destined for human consumption. Nevertheless, aquaculture production still needs to increase to fill the gap in supply and demand for fish, as the capture fisheries are stagnating over the years. Therefore, intensification of aquaculture production systems by increasing inputs such as feed has been devised as an alternative. On the other hand, intensive aquaculture has been associated with concerns related to environmental pollution in the past decades. Moreover, the increased cost of feed ingredients for aquaculture species has hampered the intensification of the sector. Therefore, alternative production systems such as biofloc technology were developed to mitigate the environmental impacts of intensive aquaculture and also to produce extra feed for cultured organisms. Due to their omnivorous feeding habit and tolerance to higher levels of suspended solids, freshwater finfishes have been the most cultured species in this system. The organic carbon sources used in the biofloc system are agricultural and industrial by-products which are cheap and readily available, making the technology economically feasible. C:N ratios of 10, 15, and 20 have been the most applied C:N ratios in the culture of freshwater aquaculture finfishes covered in this review

Manual for production of Chamo strain Nile tilapia fingerlings and preparation of fish feeds from locally available material

Climate change has resulted in increased local temperatures that in turn have increased evapotranspiration, and negatively affected the breeding grounds of several important fish species due to reduction in the water levels of water bodies (Ficke et al. 2007). The rise in local temperature also affects the physico-chemical properties of water, including temperature, pH, dissolved oxygen, salinity, and concentration of different ions in water bodies (El Morhit & Mouhir 2014). These changes negatively affect the physiological (e.g. reproduction) and behavioral dynamics of fish as well as their natural feed leading to lower production of capture fish (Chabot & Guénette 2013). To increase production of capture fish, there is need for a reliable method for mass production of fry. Although tilapia breed freely in ponds, it is important for farmers (producers) to consider using properly produced fingerlings. However, there are quality challenges with semi-natural or hormone-induced propagation of fingerlings. Quality fingerlings in tilapia aquaculture are needed for improved production. For this reason, it is advisable for farmers to generate their own fingerlings if they cannot ascertain the quality of those from other sources. Poor fingerlings result in poor harvests. Therefore, artificial propagation under controlled environmental conditions in a hatchery has become a necessity to ensure production en-masse of fry and fingerlings

The effect of Aspergillus niger on the nutritive value of water hyacinth as fish feed using solid state fermentation

Water hyacinth typically has high moisture content, low protein profile and high crude fiber content. Its value as a feed resource can be improved through solid-state fermentation with the fungi species, Aspergillus niger. This study was conducted with the aim of producing environmentally friendly and nutrient rich fish feed at low cost from water hyacinth. Water hyacinth leaf and whole plant were collected, dried, milled, sterilized and subjected to incubation with Aspergillus niger for a period of eight weeks. Fermentation resulted in an increase (p<0.05) in crude protein and ash contents, a decrease (p<0.05) in dry matter, crude fiber, nitrogen free extract and fat contents of fermented water hyacinth leaf and whole plant. The results suggested that water hyacinth with six weeks fermentation period contained the highest level of crude protein of both leaf and whole plant. Hence, biological treatment of water hyacinth using Aspergillus niger improved its nutritive value, and this finding might be used to produce fish feed and to reduce environmental pollution

Reproductive biology of Garra regressus and Garra tana (Cypriniformes: Cyprinidae) from Lake Tana, Ethiopia

The reproductive biology of Garra regressus and Garra tana was investigated by collecting monthly samples (January to December 2006) from the southern Gulf of Lake Tana, where these species are endemic.  Garra regressus has an extended breeding time from April to October while G. tana breeds throughout the year with a peak from March to July.  The mean size at maturity in both the species was not significantly different between the sexes, but G. tana had a significantly lower mean size at maturity than G. regressus in female specimens.  Absolute fecundity estimates for G. regressus ranged from 580.8–1800, while those for G. tana ranged from 538.9–2968.  Egg size frequency distribution revealed that G. regressus is a multiple spawner, while G. tana is a single spawner.  The sex ratio in the total catch of G. regressus was found to be skewed in favour of females (Chi-square, P&lt; 0.05), while those for G. tana was not significantly different from 1:1. The mean size at maturity was not significantly different between the sexes for G. tana. </div

Reproductive biology of Garra regressus and Garra tana (Cypriniformes: Cyprinidae) from Lake Tana, Ethiopia

The reproductive biology of Garra regressus and Garra tana was investigated by collecting monthly samples (January to December 2006) from the southern Gulf of Lake Tana, where these species are endemic.  Garra regressus has an extended breeding time from April to October while G. tana breeds throughout the year with a peak from March to July.  The mean size at maturity in both the species was not significantly different between the sexes, but G. tana had a significantly lower mean size at maturity than G. regressus in female specimens.  Absolute fecundity estimates for G. regressus ranged from 580.8–1800, while those for G. tana ranged from 538.9–2968.  Egg size frequency distribution revealed that G. regressus is a multiple spawner, while G. tana is a single spawner.  The sex ratio in the total catch of G. regressus was found to be skewed in favour of females (Chi-square, P&lt; 0.05), while those for G. tana was not significantly different from 1:1. The mean size at maturity was not significantly different between the sexes for G. tana. </div

Potential live feeds for larval fish culture in Ethiopia

The artificial propagation of commercially important fish species in Ethiopia is constrained by high mortality rate at the early stage of larval rearing and a subsequent poor growth performance during later stages. This is mainly due to absence of live feeds suited to the requirements of the larvae of the species. Although not organized, several studies have indicated that microalgae, copepods, cladocerans and rotifers are the dominant inhabitants in several water bodies that are the precursors in the larviculture of commercially important finfishes in the world. However, apart from studying the abundance and diversity of these important planktonic organisms, efforts made to culture any of them for use in the larviculture of commercially important fish species in Ethiopia is minimal. This may be due to the lack of comprehensive and organized information on the distribution and abundance of these important species in the context of their potential in aquaculture of live feeds in Ethiopia. The objective of this review is therefore to compile the available information on the abundance and distribution of the major potential live feed organisms in the Ethiopian water bodies with a special emphasis on freshwater live feed organisms currently used in larviculture of commercially important freshwater finfishes. In line with this, four potential live feeds (i.e. microalgae, rotifers, copepods and cladocerans) were included in the review. It is hoped that the review will provide baseline information for future research in the culture of economically important larval live feeds