0. AKU3201 PRINCIPLES OF AQUACULTURE
Natural spawning
Induced spawning

1. Problem Availability of required quantity of fish seed Seed from wild
Low seed supply

2. Broodstock –> larvae -> fry -> fingerling -> juvenile

3. Spawning habits differ considerably in different groups of fish
Season-bound spawners and spawn in particular seasons such as spring, summer, rainy season and winter
Non-season-bound ones and spawn round the year

4. Spawning conditions:
i) spawn in confined waters,
ii) others in fluviatile conditions;
iii) some migrate from freshwater to the sea or from the sea to freshwater to spawn.

5. Natural spawning
Induced spawning

6. Natural spawning
Stimulation of natural spawning conditions in ponds or tanks
Seasonal – spawn at certain season (rainy, flood, spring)
Non-seasonal – spawn throughout the year

7. Tilapia species
- Nest builders; fertilized eggs are guarded by brood parent
Sarotherodon species
- Mouth brooders
- Either male or both male/female
Oreochromis species
Mouth brooders
Female only

9. Genital papilla Nile Tilapia
Nile Tilapia = male establishes a territory & a round nest, female enter & lay eggs, male fertilized the eggs, female collects & incubate eggs in mouth, eggs yellow in colour, egss hatch in five to seven days, fry remain another 4-7 days.
Male: 2 openings
Female: 3 openings

10. 300 gm female broodstock: 250-300 eggs
Eggs fertilized by male
Female collects & incubate eggs in mouth
Eggs yellow in colour
Hatch about 5-7 days

11. Identify male & female
1 male : 3 female into hapa

12. Induced spawning Species that didn’t reproduce in captivity
Obtain fish supply outside of the normal spawning season; important for intensive culture
Develop superior strains through selective breeding & hybridization methods
Maximize survival;
1% natural spawning; 65% induced spawning

13. Induced spawning Environmental manipulation Temperature Water volumepH
Salinity
Hormone induction

15. Primary tissue involved in hormonal cascade
Hypothalamus
Pituitary gland
Gonad

16. Broodstock (Induk)
Large
Productive
Healthy
Disease-free

17. Hypophysation: Process of inducing fish to spawn through the use of hormones
E.g., Pituitary gland & other hormones

18. Commercial hormone HCG – Human chorionic gonadotropin
LHRH – Luteinizing hormone-releasing hormone
GnRH –Gonadrotropin-releasing hormone
FSH – Follicle-stimulating hormone
Ovaprim, ovaplant, ovatide

19. Pituitary gland

23. Steps in artificial propagation
Brood fish selection from nature or fish ponds
Brood fish rearing
Induce final maturation & ovulation with hormone treatment
Treatment of the male & milt collection
Stripping of the female & egg collection
Artificial fertilization
Incubation & hatching of eggs
Larvae & fry rearing

24. (1) Broodstock selection
(2) Hormone preparation & injection
(3) Stripping of eggs & sperm
(4) Fertilization & incubation
(5) Hatching & larvae

25. Sex Identification External - Shape of body (abdomen)
Colour (Male => colourful)
structure (Male => tubercles on operculum surface)
Eggs/ milt

26. Weight & inject Male - 0.25 ml/kg Female – 0.5 ml/kg
Leave ~ hours, temperature 26-28oC

27. Internal
Check for egg & milt through catheter
Gonad (dissection, histology)

28. Identify the sexes Male genital papillae – pointed
Female gential papilale – oval shape, bulging abdomen

29. INJECTION THE FISH 2 dosage level
Intraperitoneal – within the body cavity, behind either pelvic or pectoral fin
2 dosage level
A prepatory dose – brink of spawning
A final dose – induces ovulation
A time gap generally 12 to 24 hour between the dose

32. Stripping

35. Eggs

36. Male spawner Some fish – difficult to strip
Due to the anatomical structure – seminal vesicles
Need to sacrifice the fish to collect the milt
Avoid contact with water or the spermatozoa lose its ability to fertilize mature fish eggs.
Milt can be stored in a refrigerator for 1-2 days

37. Collection of milt from catfish testis

45. Spread on a screen (mesh size 1 mm), hatchling will pass the screen & dead eggs & shells remain on the screen