2.2 Japanese catfish The characteristic of the Japanesecatfish is the normal for any Silurusspecies.
It has a small dorsal fin which is dark grey at its sides. Theirstomach is white colour with sporadic white dabs at each side. They also obtainbarbels as any common catfish. However, the specialty of the Japanese catfishis having one pair of the mandibular barbell which is longer than their headwhile another pair of the mandibular barbell is 1/3 to 1/5 of the total lengthof their maxillary barbell (Liu, 1990). During the adolescent stage, the fishcan be around 6 to 7 cm as their standard length. Also, amid this stage, they haveone additional combine of mandibular barbell however it will deteriorates as itenters the adulthood (Atoda, 1935). Furthermore, Japanesecatfish can create its home in or under of stream or at lake banks, old logs,shakes or even under rocks.
While others would discover openings in banks, andsome can make the gaps themselves. The spawning season will come in the springor late spring from May up to June. They are able to spawn eggs around 5000 upto 10000 eggs which depends on their age and size.
While for their sex, it canbe seen an apparent sex ratio of the species is extremely high toward femalesto males. They are intraspecific variety in their regenerative nature,especially during mating conduct, as it has been research inside theneighbourhood populaces in Japan (Maehata, 2007). In Japan, a pastinvestigation of the Japanese catfish in almost various lake has indicates a diversemating conduct.
For instances, in the lake Biwa populaces it had demonstrated asettled succession of activities, for example the pursuing, the sticking, theenclosing with pressing by the male, and by hovering of the matched fish, andthe females are constantly enveloped by a solitary male (Maehata, 2002), whileat the Ooi lake and at the Fuefuki lake, the populations does not demonstratesuch the same behavioural sequence which was the process of enfolding afemale’s body by a male. The circling by the paired fish has also not been seenbut instead the females will usually enfolded by around two different males(Maehata, 2007). In the spawning activities, the Japanese catfish will scatter their eggs. This was believedto be aimed at reducing the number of juvenile mortality rate (Katano et al., 1988). The male is generally theall-time caretaker and defender of the eggs. As the fry will continueto grow to adult phase, their diet will begin to increases as many type ofanimals such as the crustaceans, the clams and also small fish become theirfood (Katano et al., 1988).
In almostall the matured adult fish are active and feed during night time. However, thisfish also feed in condition such as cloudy and also in opaque waters during sunlightis available. The hunting method relies upon their sense of scent and taste dueto the catfish having very poor sight (Maehata, 2007). When the larvae had agedto juvenile and become matured, they will then began to form schools and movetogether.
Moreover, they do notpossess any migrating characteristic such as travelling downstream and upstreamriver. But will spend a lot of their lives inlakes bottom, the reservoirs and river streams. 2.3 African catfish The African catfish is a prevailingfreshwater fish. It can develop to in the range from 1.4 up to 2m long and can also weigh in from a minimum of 8kgs up to59kgs (Freyhof, 2016). For its characteristic, the body colouration canfluctuates from olive green, to darker and dark with the flanks frequentlyuniform dim to olive-yellow with dim slate or greenish darker back (FAO, 2012).In its underparts, the colours are pale olive to white and are mottledunpredictably with dull tanish green, or consistently gleaming olive.
It is heavy bone with a levelheaded and obtaining premaxilla while having lower jaw pointed teeth organisedin few lines. Meanwhile, it also has four pairs of long trailing sensory organsknown as barbels around its mouth (A-Z animals, 2008). In addition, the catfishhas a high number of gill rakers differing from 24 to 110. The number willincrease with the size of the fish. These fish are an insatiable predator and will likely eat almosteverything in its sight (Ataguba et al.
,2012). Their prey also includes several organism such as the insects, the crabs,the plankton, the snails, small fish, small birds, and many more (Ibrahem,2011). It is generally an individual bottom feeder, however they are known tobe to a great degree versatile to conditions and can move in groups at thewater surface. Meanwhile, it can additionally shows an assortment of strongly behavioursuch as sucking the surface for earthbound creepy crawlies and also some plant pieces that was washed into the water by overwhelmingrains and pack-hunting of small cichlids. The growth is generally rapid, wherethe fish can obtain their maximum size within a couple of years (FAO, 2008).African catfish are generally conveyed far and widearound the world. The species can extend from South Africa up to Middle, Westand North Africa.
It is likewise had been dispersed around different continentsuch as the Middle East and Eastern Europe. Furthermore, they are alsoadditionally similarly introduce in Jordan, Lebanon, Israel and Turkey. It hasalso been brought into most of the different nations in Africa, and also a fewin Europe, Asia and South America. Similarly to some other species, China also introduced itwithin its rice fields and is currently holding the position of among the mainproducing countries (De Silva, 2010). The pattern for African catfish culturehas been increase throughout the following years since it introduction as oneof the biggest fish species in aquaculture.
Even in the market for Africancatfish in the sub-Saharan Africa has been increasing and evolving each year(FAO, 2010).