This document provides information on the African catfish (Clarias gariepinus). It discusses the biology of C. gariepinus and the closely related species C. anguillaris. It also describes the natural breeding and artificial propagation of C. gariepinus, including hormone treatment of broodfish, incubation and hatching of eggs, nursing of fry, and feeding regimes for early fry and advanced fry in hatcheries. Semi-intensive polyculture of catfish and tilapia in earthen ponds is also summarized.

1. AFRICAN
CATFISH
(Clarias gariepinus)

2. Introduction
• More than 100 species of the genus Clarias have
been described in Africa.
• Teugels (1984), who recognizes only 32 valid
species.
• C. gariepinus (Burchell, 1822), synonymous with C.
lazera is the most important for aquaculture.
• Of secondary importance is C. anguillaris. This
species has a more restricted distribution, occuring
in Mauritania, in most West Africa basins and in the
Nile.
• Thus, C. anguillaris lives in most river basins
sympatrically with C. gariepinus.
• African catfishes inhabit calm waters from lakes,
streams and rivers to swamps, some of which are
subject to seasonal drying.

3. Clarias anguillaris
Clarias lazera

4. BIOLOGY
• Displaying an anguilliform shape, having an
elongated cylindrical body; dorsal and anal fins are
extremely long, nearly reaching or reaching the
caudal fin; both fins contain only soft fin rays.
• The outer pectoral ray is a spine.
• Pelvic fin normally has six soft rays.
• Head is flattened, highly ossified and the body is
covered with a smooth, scale less skin.
• 4 pairs of unbranched barbels one nasal, one
maxillar (longest and most mobile) on the vomer
and two mandibulars (inner and outer) on the jaw.
• Tooth plates are present on the jaws as well as on
the vomer.

5. • Apparently has little hydrostatic function.
• Buoyancy is controlled by air carried in the
suprabranchial chamber.
• Clarias species have a scale less skin.
• Darkly pigmented in the dorsal and lateral parts of the
body.
• colour is uniform or marbled and ranges from grayish
olive to blackish according to the substrate.
• Exposed to light the colour becomes lighter.
• A suprabrachial or accesory respiratory organ,
composed of a paired pear-shaped air chamber
containing two arborescent structures is generally
present.
• In air-situated water catfish can survive without air
breathing.
• It enables them to migrate over land.
• Reports of Clarias “walking” occur widely in literature.

6. • C. gariepinus feed mainly on aquatic
insects, fish and debris of higher plants.
• They also feed on terrestrial insects, molluscs
and fruits It may be considered as an
omnivorous fish with a high tendency to
predation.
• The catfish grasps its prey by sunction.

7. NATURAL BREEDING
• Ovaries of C. gariepinus are paired elongated
organs situated dorsally in the body cavity.
• The lamellae contain oogonia and oocytes in
follicles at different stages of development.
• Each ovary extends posteriorly into a distinct
oviduct.
• Matures females have very large ovaries which fill
the body cavity and may constitute up to 25-3-% of
their total body weight.
• In nature the ovaries of a mature population usually
represent from 7-12% of the total body weight of
females (Micha, 1973; Bruton, 1979).

8. • The testes are paired and connected by fused
spermatic ducts which open into an elongated,
posteriorly pointed, urogenetal papilla.
• The testes are externally differentiated into two
distinct regions: a milkish-white, opaque anterior
part, the true testes (spermatogenesis and sperm
storage) and a semi-transparent posterior part
consisting of a series of finger-like lobes, the
seminal vesicles (glandular function).
• The testes only represent a maximum of 2-4% of the
total body weight.
• The median size of fish at first maturity shows
remarkable variation and ranges from 260-750 mm
total length.
• Maturity was reached towards the end of the
second year by most of the population.

9. • Under artificial conditions catfishes mature after
about 6 months when they have attained a weight
of about 200g.
• Feeding and water temperature are major factors
regulating the age/size at first maturity.
• Eggs of mature females are
-small (1.2-1.6mm), slightly oblong and have a
yellowish-green color.
-nucleus in the center is clearly visible.
-1 gram of stripped eggs contains between 600900 eggs.
• Spawning takes place mostly at night in recently
inundated marginal areas of lakes, stream or river.
• Courtship and mating take place between isolated
pairs in shallow waters.

10. • There is no parental care for ensuring
the survival of the catfish offspring
except by careful choice of suitable
site.
• Development of eggs and larvae is
rapid and larvae are able to swim
within 48-72 hours after fertilization.
• Temperature and flooding are
probably the decisive stimuli for
gonadal development and spawning.

11. Artificial Propagation
and
Fry Production

12. ADAVANTAGES:
• Better rates of fertilization and hatching;
• protection against enemies and unfavorable
environmental conditions;
• better conditions for growth and survival

13. Broodstock and hatchery
management
• 100 males as broodstock for propagation
• 100 females as broodstock for propagation
• 100 males conditioning
• 100 males for conditioning

14. Breeders are kept in rectangular tanks of about 1 to
1.5m3.
Water inflow is at one end, while the water flows
out at the
Other end througha turn-pipe.
Oxygen concentration in the water should not fall
below
3mg/l.
Optimum temp must be 25 degree celsius.

15. Adequate food supply is also of
foremost importance to broodfishes.
A well balanced compounded diet
containing all the essential nutrient
requirement, particularly amino acids,
vitamins and minerals is a prerequisite
for proper gonadal development.

16. of
African catfish
On-growing

17. Semi- intensive polyculture of catfish
and tilapia
•One way to enhance the production of
tilapia ponds is to stock them together
with a predatory fish such as C.
gariepinus, which controls the excessive
reproduction
•Semi-intensive polyculture of catfish and
tilapia in earthen ponds aims at
minimizing inputs.

18. Preparation of ponds
Pond preparation is done in the
usual way. In addition the pond should
be equipped with at least one compost
crib placed in a corner near the inlet
and made of bamboo or wooden stakes.
Compost
crib

19. Pond stocking
•Fingerlings are stocked as soon as
the ponds are filled with water. The
stocking rate depends on the
marketable size.
•If higher marketable sizes are
desired, catfish may be stocked at a
lower rate, but not less than 0.5
fingerling per square meter.

20. Pond fertilization
•After stocking, the natural production
of the pond should be regularly
maintained by adding mainly organic
fertilizers. Inorganic fertilizers,
generally more expensive, are usually
not necessary and their use should be
restricted to areas with very poor soils
and/or acid water.

21. Supplementary food distribution
•While some production (up to about 30–
50 kg/are/year) may be obtained only by
relying on the natural pond production
increased through fertilization, successful
polyculture of catfish and tilapia should
involve supplementary feeding.
•The most economical ingredients which are
locally available in significant quantities should
be used. If available and economically feasible, oil
cakes, which are rich both in energy and protein
are preferable. They should be ground before
feeding.

22. Hormone treatment
of broodfish

23. The success of the artificial
propagation, depends on the
number of such dormant
ovocytes in the ovary.
Females selected for
induced ovulation and
spawning should show :

24. • a well-rounded and soft abdomen
which extends anteriorly past the
pectoral fins to the urogenital
papilla. Mature eggs, showing
clearly the nucleus in the
centre, can be obtained easily by
slight pressure on the abdomen;
• a genital opening which is swollen
and sometimes reddish or pink in
colour.

25. The following
hormones/compounds have
been successfully used to
induce artificial propagation
with C. gariepinus :
• acetone dried carp pituitary, 4
mg/kg body weight (BW);
• acetone dried or fresh Clarias
pituitary, 1 gland/female;

26. • Human chorionic gonadotrophin
(HCG), 4 IU/g BW;
• Deoxycorticosterone Acetate
(DOCA).

27. Generally the hormone solution is
injected into the dorsal muscles
above the lateral line, just below the
anterior part of the dorsal fin, using
a graduated syringe (2 – 5 ml). The
needle is placed parallel to the fish,
pointing posteriorly at an angle of
approximately 30 .

28. After injection, the injected area is
rubbed with one finger to distribute the
hormone suspension evenly throughout
the muscles.
When more than 10 females are selected,
it is advisable to separate them into two
groups of equal
numbers and to inject them with a time
interval of about 30–60 minutes between
groups. This will give the operator more
time for stripping the females at

29. the right moment. Females are
generally injected in the evening.
The injection time is calculated
according to the water temperature
and the desired time of stripping .
Handling of breeders should be done
with care using a wet towel. After
injection, the females are gently
replaced in their covered containers.
There is no need to suture the genital
orifice of catfish to

30. prevent wastage of ovulated
eggs, since the females do
not scatter their eggs
without the presence of a
male.

31. Pond Nursing of Catfish Fry
be nursed in small earthen ponds for about one
month up to the fingerling stage.
200 to 1 000 m2 size may vary. Rectangular ponds
ranging from 10 × 20 m to 25 × 40 m.
 good standing crop of zooplankton must be
established.
non-polluted, slightly alkaline water (pH 6.5–8) and
well exposed to sunlight.
The water supply,
(i) replace water losses due to evaporation, seepage or
leakage,
(ii) fill the nursery pond rapidly,
(iii) exchange the water if oxygen depletion or
chemical water pollution occur.

32. wide water supply pipe or channel.
draining structure.
the pond should be fenced by a fine mesh
netting or roofing sheets, height 1–1.5
m, should be embedded for about 10 cm.
The inflowing water should be filtered through
a screened box placed on the inlet pipe.
The appropriate moment for stocking fry is
about 3 to 5 days after fertilization.
2–3 day-old fry (two-thirds of yolk has been
absorbed) or with 6–7 day-old fry, fed
previously with zooplankton or Artemia.

33. SCHEDULE FOR SYNCHRONIZED ARTIFICIAL PROPOGATION
AND POND NURSING ACTIVITIES
Day
Artificial propagation
Nursing pond
-4
Injection of broodfish
-3
Stripping and incubation
Cleaning ponds: cutting grass,
removal of silt, etc.
-2
Hatching, separation of normal
larvae and spoiled eggs
Liming
-1
Cleaning larval troughs
Water filling and fertilization
-
0
-
Stocking of fry
+ 3, 7, 10
14, 17, 21
-
Fertilization
+ 26–30
-
Harvest

34.  Once the fry are stocked, a high standing crop of
zooplankton must be maintained in the nursery
ponds by regular fertilization to ensure good growth
and high survival.
 5 kg manure, 0.1 kg nitrogen and 0.025 kg
phosphorus per 100 m2 of pond.
 Feeds are distributed twice a day at a rate (per 100
m2) of 0.5 kg during the second week after
stocking, 0.75 kg during the third week, and 1 kg
during the fourth week.
 0.5–1 mm but the food composition remains the
same.
 After about one month, the fingerlings (weighing 2–5
g) are harvested from the nursing pond. The
fingerlings are collected in a concrete or wooden
harvest box fixed to the outlet pipe.

35. PROCUREMENT OF MILT

36. PROCUREMENT OF
MILT
- Milt is obtained by sacrificing one male and
dissecting the testes.
-milt can then easily be squeezed out and
collected into a small bottle.

37. FERTILIZATION
OF EGGS

38. FERTILIZATION OF EGGS
-a few drops of milt solution
are added into the eggs
and the sexual products
are mixed by gently
shaking the bowl.
-physiological salt solution is
added.
-the eggs are fertilized by
adding a small amount of
clean water.

39. INCUBATION AND HATCHING
OF EGGS

40. INCUBATION AND
HATCHING OF EGGS
-fertilized eggs are incubated in stagnant or
running water in troughs containing small
trays or boxes.
-incubator is filled with clean, well
oxygenated water.

41. INCUBATION AND
HATCHING OF EGGS

42. Nursing of Early Fry
•After 3-4 days, when about two-thirds of the yolk
sac has been absorbed, the larvae (weighing
about 2-3 mg) become early fry.
•Once the yolk sac is fully absorbed, the fry must
find adequate food to ensure proper development
•During the early stage the development of the main
organs will be completed after 10-18 days when
the accessory air-breathing organ has developed.
•Catfish fry (weighing 30-50 mg) frequently rise to t
he surface to breathe air. They become then
advance fry.

45. Hatchery Nursing of Early
Fry
• Early fry are kept in the larval rearing troughs, and
the rearing troughs
•Catfish fry have been nursed successfully with the
following first feed:(1) live or frozen zooplankton (2)
live or frozen nauplii of brine shrimp Artemia salina;
(3) decapsulated Artemia eggs.
•A variety of artificial dry feeds such as complete diets,
commercial trout starters, microencapsulated egg diet,
etc. have been tested- result: the food intake was
considerably reduced especially a few days after initial
feeding; growth was poor and mortality high.

46. • Recently rather good growth and high survival have been
obtained using an artificial dry feed. This feed, containing
55.4 % of crude protein. Unfortunately this type of yeast is
not available in most African countries.
• Feeding live zooplankton from nearby fresh water fish
ponds seems to be the most reliable technique for African
countries, since importation of Artemia eggs is either
difficult or prohibited.
• Feeding every 3-4 hours during 24 hours is even better.

47. •Hungry fry swim vigorously in the water
column, whereas well-fed fry gather in clusters on
the bottom of the tank and have a considerably
swollen belly.
•The stomach contents of the fry can easily be
monitored since their ventral sides are transparent.
•Thus fry fed on Artemia nauplii or decapsulated
Artemia eggs have a distinct orange belly after
feeding.
•Mortality during the early fry stage is negligible
under optimum nursing management.

49. Hatchery Nursing of
Advanced Fry
• The early fry stage ends when the fry fill up their suprabranchial air chamber with air.
• The advanced fry are transferred to nursery troughs. Water
depth is increased to 0.5m.
• Transferring of advanced fry is a delicate procedure, and
must be done by carefully siphoning fry into bucket. The
contents of the bucket are then gently released into the
nursing device.
• Each nursing trough, filled with 160-200 L of water, may be
stocked with 10,000 fry (50 to 65 fry/L).

50. • The water supply must be adjusted once a
day according to the dissolved oxygen
content of the outflowing water. The
recommended minimum dissolved oxygen
level for advanced fry nursing is 3 mg/l.
FEEDING
• There are several physical and chemical
requirements for artificial dry feeds.
 0.35-0.5 mm for fry of 50-100mg
 0.5-0.75 mm for 100-250 mg fish
 0.75-1.25 mm for 250 mg-1 g fish

51. • From 10-18 days after hatching the fry will
accept artificial diets. The change from live
food to artificial dry feed is a major turning
point in the life of hatchery nursed catfish.
• Artificial feed can be administered manually
(6 times a day) or automatically with feeders.
Over feeding must be avoided since this is
believed to be the main cause of disease
outbreaks at this stage of development.
• After 5-8 weeks, the advanced fry will weigh
about 1 g. at this size, they can be harvested
and transferred to fattening ponds. A survival
of about 70-80% can be obtained under
optimal husbandry management.

54. • Yolk Sack Larvae - Yolk sack larvae are 3 day old,
free swimming larvae that require their first food
shortly after receiving. Yolk sack larvae are suitable
for stocking into plankton ponds or can be raised in
tanks. Advanced larval rearing experience and
appropriate facilities are required if tank- rearing is
going to be attempted.
• We pack up to 50,000* yolk larvae per box. Minimum
order 300,000 tails