2.2 Their stomach is white colour with sporadic

2.2 Japanese catfish

 

The characteristic of the Japanese
catfish is the normal for any Silurus
species. It has a small dorsal fin which is dark grey at its sides. Their
stomach is white colour with sporadic white dabs at each side. They also obtain
barbels as any common catfish. However, the specialty of the Japanese catfish
is having one pair of the mandibular barbell which is longer than their head
while another pair of the mandibular barbell is 1/3 to 1/5 of the total length
of their maxillary barbell (Liu, 1990). During the adolescent stage, the fish
can be around 6 to 7 cm as their standard length. Also, amid this stage, they have
one additional combine of mandibular barbell however it will deteriorates as it
enters the adulthood (Atoda, 1935).

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Furthermore, Japanese
catfish 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, and
some can make the gaps themselves. The spawning season will come in the spring
or late spring from May up to June. They are able to spawn eggs around 5000 up
to 10000 eggs which depends on their age and size. While for their sex, it can
be seen an apparent sex ratio of the species is extremely high toward females
to males. They are intraspecific variety in their regenerative nature,
especially during mating conduct, as it has been research inside the
neighbourhood populaces in Japan (Maehata, 2007).

In Japan, a past
investigation of the Japanese catfish in almost various lake has indicates a diverse
mating conduct. For instances, in the lake Biwa populaces it had demonstrated a
settled succession of activities, for example the pursuing, the sticking, the
enclosing with pressing by the male, and by hovering of the matched fish, and
the females are constantly enveloped by a solitary male (Maehata, 2002), while
at the Ooi lake and at the Fuefuki lake, the populations does not demonstrate
such the same behavioural sequence which was the process of enfolding a
female’s body by a male. The circling by the paired fish has also not been seen
but 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 believed
to be aimed at reducing the number of juvenile mortality rate (Katano et al., 1988). The male is generally the
all-time caretaker and defender of the eggs.

As the fry will continue
to grow to adult phase, their diet will begin to increases as many type of
animals such as the crustaceans, the clams and also small fish become their
food (Katano et al., 1988). In almost
all the matured adult fish are active and feed during night time. However, this
fish also feed in condition such as cloudy and also in opaque waters during sunlight
is available. The hunting method relies upon their sense of scent and taste due
to the catfish having very poor sight (Maehata, 2007). When the larvae had aged
to juvenile and become matured, they will then began to form schools and move
together. Moreover, they do not
possess any migrating characteristic such as travelling downstream and upstream
river. But will spend a lot of their lives in
lakes bottom, the reservoirs and river streams.

 

 

2.3 African catfish

 

The African catfish is a prevailing
freshwater 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 to
59kgs (Freyhof, 2016). For its characteristic, the body colouration can
fluctuates from olive green, to darker and dark with the flanks frequently
uniform 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 mottled
unpredictably with dull tanish green, or consistently gleaming olive.

It is heavy bone with a level
headed and obtaining premaxilla while having lower jaw pointed teeth organised
in few lines. Meanwhile, it also has four pairs of long trailing sensory organs
known as barbels around its mouth (A-Z animals, 2008). In addition, the catfish
has a high number of gill rakers differing from 24 to 110. The number will
increase with the size of the fish. These fish are an insatiable predator and will likely eat almost
everything 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 to
be to a great degree versatile to conditions and can move in groups at the
water surface. Meanwhile, it can additionally shows an assortment of strongly behaviour
such as sucking the surface for earthbound creepy crawlies and  also some plant pieces  that was washed into the water by overwhelming
rains and pack-hunting of small cichlids. The growth is generally rapid, where
the fish can obtain their maximum size within a couple of years (FAO, 2008).

African catfish are generally conveyed far and wide
around the world. The species can extend from South Africa up to Middle, West
and North Africa. It is likewise had been dispersed around different continent
such as the Middle East and Eastern Europe. Furthermore, they are also
additionally similarly introduce in Jordan, Lebanon, Israel and Turkey. It has
also been brought into most of the different nations in Africa, and also a few
in Europe, Asia and South America. Similarly to some other species, China also introduced it
within its rice fields and is currently holding the position of among the main
producing countries (De Silva, 2010). The pattern for African catfish culture
has been increase throughout the following years since it introduction as one
of the biggest fish species in aquaculture. Even in the market for African
catfish in the sub-Saharan Africa has been increasing and evolving each year
(FAO, 2010).