what you need to know about the common Catfish species
African Catfish, Vundu and Heteroclaries
Aquaculture production of the African catfishes Clarias gariepinus and Heterobranchus longifilis has been practiced for a long time in Africa. Increased productivity of fry and fingerlings with attributes of faster growth rates and better environmental tolerance is sine qua non to ensuring fish food security in Africa. Genetic techniques are therefore needed to ensure that a faster growth rate leading to a shorter production cycle as well as a greater tolerance for poor water condition is achieved.
African catfishes Clarias gariepinus (sharptooth)
They are found throughout Africa and the Middle East and live in freshwater lakes, rivers, and swamps, as well as human-made habitats, such as oxidation ponds or even urban sewage systems. The African sharptooth catfish was introduced all over the world in the early 1980s for aquaculture purposes, so is found in countries far outside its natural habitats, such as Brazil, Vietnam, Indonesia, and India
C. gariepinus has an average adult length of 1–1.5m. It reaches a maximum length of 1.7m and can weigh up to 60 kg. These fish have slender bodies, flat bony heads, notably flatter than in the genus Silurus, and broad, terminal mouths with four pairs of barbells. They also have large accessory breathing organs composed of modified gill arches. Also, only the pectoral fins have spines.
Spawning mostly takes place at night in the shallow, inundated areas of the rivers lakes and streams. Courtship is preceded by highly aggressive encounters between males. Courtship and mating take place in shallow waters between isolated pairs of males and females. The male lies in a U-shape curved around the head of the female, held for several seconds. A batch of milt and eggs is released followed by a vigorous swish of the female’s tail to distribute the eggs over a wide area. The pair usually rests after mating (from seconds up to several minutes) and then resume mating. Development of eggs and larvae is rapid, and the larvae are capable of swimming within 48–72 hours after fertilization
- African catfish has been realized to be a very suitable species for aquaculture, as:
- It grows fast and feeds on a large variety of agriculture byproducts
- It is hardy and tolerates adverse water quality conditions
- It can be raised in high densities, resulting in high net yields.
- In most countries, it fetches a higher price than tilapia, as it can be sold live at the market
- It matures and relatively easily reproduces in captivity
- It tolerates difficult conditions in aquaculture
Vundu Heterobranchus longifilis
The vundu (Heterobranchus longifilis) is a species of large air-breathing catfish found widely in rivers and other freshwater habitats of sub-Saharan Africa, as well as the Nile. It is also called the solomon fish The vundu is the largest true freshwater fish in southern Africa, reaching up to 1.5 m in length and 55 kg in weight. Few other catfish have such large second dorsal fins (adipose fins) or such long barbels as do the vundu. Its barbels nearly reach to the origin of the pelvic fin. The color of Heterobranchus longifilis is light to dark olive-brown on its dorsal surface, getting lighter over the mid-body to a light brown. Its belly is off-white. Fins are usually light brown.
In aquaculture, it is sometimes hybridized with the African sharptooth catfish (Clarias gariepinus), resulting in offspring known as “Hetero-clarias”.
The vundu is found widely in rivers and other freshwater habitats of sub-Saharan Africa, only extending beyond this region in the Nile (although it is rare in the lower sections of this river). Among others, it is found in the Benue River, Volta River, Niger River, Gambia River, Senegal River, Lake Chad, Omo River, Congo River Basin, Lake Rukwa, Lake Kariba, Zambezi River, Lake Tanganyika and Lake Edward.
The vundu is generally uncommon, but it is not considered threatened despite having declined locally. Most active at night, it feeds on any available food, including invertebrates and insects when small, then fish and other small vertebrates when large. It scavenges off large carcasses and offal from riverside villages. It can live for 12 or more years.
Heterobranchus spp have a growth rate twice as fast as that of Clarias gariepinus while the latter survives in poorly oxygenated water. The vundu catfish can survive out of water for extensive periods of time.
Hybridization between these two clariid catfishes thus produces offsprings that possess a combination of these desirable qualities.
Clarias gariepinus could be easily crossed with Heterobranchus longifillisto get the so-called hybrid Hetero-clarias. This cross has advantages over the Clarias gariepinus
- fish cannot reproduce itself (so it won’t spend energy on reproduction)
- fish has white meat (could be preferred by the customer)
A disadvantage of the Hetero-clarias hybrid:
- Susceptible to stress
Other qualities of this species include:
- Heteroclarias spp are very rugged and disease resistant, and they consume less feed when compared to Clarias species.
- They attain bigger sizes than Clarias spp, and they weigh much higher at harvest.
- They thrive well on a wide range of plant protein-based fish feeds.
- Longer post-harvest survival, thus preferable to buyers.
- Improved taste due to its white flesh.
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