research work in aquaculture

1. The steadily growing importance of fish farming has
compelled improvements in the technologies necessary for
securing the initial and basic requirements for productive
aquaculture; namely the production of fish seed for stocking.
Fish culture today is hardly possible without the artificial
propagation of fish seeds of preferred cultivable fish species.
The need for the production of quality fish seed for stocking
the fish ponds and natural water bodies has indeed increased
steadily (Brain and Army, 1980). Artificial propagation
methods constitute the major practicable means of providing
enough quality seed for rearing in confined fish enclosure
waters such as fish ponds, reservoirs and lakes (Charo and
Oirere, 2000)

2. TYPES OF REPRODUCTION IN CATFISH
There are two main types of reproduction in catfish they
are:
 Natural reproduction
 Artificial or Induced reproduction

3. NATURAL REPRODUCTION
Natural spawning is usually done without hormonal
treatments. This is through the simulation of natural
spawning conditions in ponds or tanks. It also occurs
naturally in the wild .
Some major advantages of this natural system of reproduction
in catfish is that it is cost effective and it requires little or no
time investment.
Major disadvantages are that few of the fry survives to the
fingerling stage. Another disadvantage is that the number of
fertilized eggs cannot be determined.

4. ARTIFICIAL REPRODUCTION
This involves the use of hormone to stimulate the egg into
ovulation. There are basically two types of induced
reproduction. They include semi-artificial reproduction
(where the final maturation of gametes is achieved through
the administration of hormones) and the artificial
reproduction (where the fish are injected with hormone to
stimulate ovulation and the eggs are stripped from the female
brood fish manually. Fertilization is then done manually and
the eggs are incubated for hatching (Akankali et al., 2011).

5. ADVANTAGES OF ARTIFICIAL REPRODUCTION
 Fish seed is guaranteed all year round
 Fish seed is obtained outside the normal environment
 It increase the survival rate
 It improve quality by crossing two different parents
(hybridization)
DISADVANTAGES OF ARTIFICIAL REPRODUCTION
 The whole process is laborious, highly technical and energy
sapping
 The donor male fish is sacrifice hence loose of one fish
 It a very expensive method it that it require construction of
houses and tanks

6. STEPS IN ARTIFICIAL REPRODUCTION
The artificial propagation of cat fish involves a chain of activities
similar to natural production. For example, the process involved in
the artificial propagation of Clarias gariepinus is:
→ Brood fish selection from nature or fish ponds
→ Brood fish rearing
→ Inducing final maturation and ovulation with hormone
treatment
→ Stripping of the female and egg collection
→ Artificial fertilization
→ Incubation and hatching of eggs; and
→ Larvae and fry rearing.

7. Plate 1: Show the female brood stock strip for egg collection.
Image Source: Google images

8. PROCUREMENT OF SPERM
The spermatozoa from a male spawner fish are obtained an
hour to stripping. It is difficult to strip the male for milt. This
is probably due to the anatomical structure of the seminal
vesicles. Therefore, milt is obtained by sacrificing a spawner
male fish. Its testes are dissected and small incisions are made
into the cream colored lobes of the testes. The milt can easily
be squeezed out and collected into a vital or small bottle. This
process can obtain several droplets of milt. Milt can be diluted
with physiological saline solution. Contact with water should
be avoided. Otherwise, the spermatozoa lose its ability to
fertilize mature fish eggs. Milt solution can be stored in a
refrigerator for one or two days without affecting its activity
(Nwadukwe et al., 1991).

9. Plate 2: Show the male brood stock sacrificed for sperm collection.
Image Source: Google images

10. COMMON HORMONES USED IN INDUCED
REPRODUCTION
 OVAPRIM
 Human Chorionic Gonadotropin (HCG)
 Carp Pituitary Extract (CPE)
 Leutinizing Releasing Hormone

11. FERTILIZATION
The union of the male’s spermatozoa and the female’s mature
eggs to form a zygote is referred to as fertilization. In fish, the
fertilization period is limited. This is because; fish eggs swell
immediately when in contact with water, resulting in the
micropyle closure. For common carp, the fertilization period
is within 45-60sec. In most other fish species, it is limited to
few minutes. Special precaution must therefore be taken to
the application of water during artificial fertilization. Three
methods are commonly adopted in the artificial fertilization
(Akankali et al., 2011).

12. Plate 3 Showing an incubator where eggs are incubated
Image Source: Google images

13. CONCLUSION
It has been stated that Nigeria is a protein
deficient country. Fish stands as a cheap source
of animal protein. In order to make fish (and
protein) readily available, artificial reproduction,
through which maximum production is usually
achieved, should be encouraged so as to meet
the high demand for fish and protein in general
in the increasing population.

14. Thank You