Freshwater fisheries has a significant contribution to development as an important source of human proteins as well as in sport fishing and aquarium. Despite their importance, both wild and aquaculture fish suffer from a problem of parasitism, notably Diplostomum species, causing fish mortalities particularly in fingerlings. Although a considerable effort in understanding Diplostomum species taxonomy, biology and control of fish parasites has been well developed in the northern hemisphere, the knowledge of these aspects in Africa is not clearly known. Therefore the present work reviews the aspects of biology and taxonomy of African Diplostomum. The traditional approach to uncover these aspects would be to complete the life cycles in the laboratory, which would lead to morphological characterisation of all life cycle stages. However, establishing and maintaining life cycles of Diplostomum species is difficult, laborious and expensive. Although, molecular methods have been proven to provide an alternative solution, are not common in Africa due to lack of equipment and expertise. However, improvement of some weaknesses for some studies like providing pictures or diagrams of the Diplostomum species found is recommended. In addition, for laboratories that have the capacity to do molecular analysis, the use of a familiar molecular marker like a barcode region could be a prospective development in future.

There is a huge potential in freshwater aquaculture in the EU and in other countries in the World. As for the World food demand fish had the second highest consumption levels, at 27.9 percent in 2014. There will be a sharp increase in demand for fish and aquaculture products as the UN FAO projects around 9 billion people living our planet by 2050. The economy has already started its adaptation. While the World aquaculture production has increased from 7 to 82 million tonnes per year from 1990, there is no rise in the EU where we can observe a stagnation in production around 1.26 million tonnes annually. The EU has its potential: coastline around 68 thousand km, 500 thousand natural lakes, etc. Next to seawater aquaculture there are several freshwater fish species such as trout, carp or catfish whose production could be radically increased by investing, innovating and creating many new jobs in the freshwater sector. A small country, Hungary can show good examples in pond and intensive fish farming despite the country has not reached its full potential yet. The boost could be managed by increased grants and other incentives for investments, innovation, cooperation and promotion. The valuable ecological services which fish farmers provide year to year have also to be rewarded. So, let’s start to act.

Study conducted in Kwanza, Trans-Nzoia County to determine the colonization pattern of benthic macroinvertebrates in earthen fish ponds. This was done to ascertain the right stocking time of ponds when the natural fish food is in plenty. Two ponds were used for this study; one was treated with organic manure while the other was not fertilized. Sampling for physico-chemical parameters were then taken immediately after filling the ponds and repeated weekly for six weeks while benthic macroinvertebrates were first sampled after week 1 and repeated weekly for six weeks. The results obtained were compared between the two treatments and per treatment over time. There were significant differences in most parameters over the weeks and between the treatments. Attainment of suitable conditions for stocking was however at week 3 for fertilized and week 4 for the non-fertilized contrary to the usual two week period advised by most procedures.

Environmental enrichment can be an effective tool to improve rearing efficiencies during hatchery production. This study evaluated the effectiveness of two different vertically-suspended arrays in circular tanks on the growth of juvenile rainbow trout Oncorhynchus mykiss. Treatments consisted of an array of suspended aluminum rods, an array of suspended aluminum angles, or no suspended structures (control) in this 141 day study. Weight gain and feed conversion ratio were significantly improved in fish reared in tanks containing either of the suspended structures compared to unenriched control tanks. The use of either vertical rods or angles is recommended during rainbow trout rearing in circular tanks, although using angles may be more desirable because they require less material to construct.

The present work aimed to estimate the toxicity of cadmium and their common carp Cyprinus carpio fish, as well as the effect of different concentrations of Cadmium and some haematological parameters. such as, the red blood cells (RBC), white blood cells (WBC) and haemoglobin (Hb) Survival mortality was observed in the blood of Common carp Cyprinus carpio treated with Abutilon indicum extract and the result showed that the RBC counts, WBC counts, Hb, Survival mortality were much increased when compared to the control. 8, 16, 24 and 32 of RBC, WBC, and haemoglobin, Survival mortality levels were P<0.05> significantly elevated in the experimental fish over the control and the WBC level was decreased significantly P<0.05> in experimental fish.