Distinguish between good and bad quality of fish seed
Vigorous and healthy stocking material can only ensure good crop of fry/fingerling. It is advised to check condition of the fry before stocking in rearing ponds.
| Sl. # | Point of Observation | Good fry | Bad fry |
| 1. | Body shape | Well formed body | Emaciated/Lean with relatively bigger head |
| 2. | Body colour | Bright, shiny | Fade colouration |
| 3. | Scales | No spots of missing scales | Lose scale and spots without scale |
| 4. | Movement | Active and exhibi tnormal movement | Lethargic |
| 5. | Reflex | Immediately react to touch and try to escape | Weak response |
| 6. | Touch | Slippery texture of the body | Rough body |
Estimating number of Fry and Fingerling
Follow the undermentioned instructions for estimating the number of fry/fingerling.
Take fry/fingerling in a known capacity of sieve cup and count the number of fry/fingerling per cup. Repeat the same for 4–5 times and calculate the average capacity of the cup in terms of number for fry/fingerling.
Take a bigger container with netted bottom and measure the capacity of the container in terms of the measured cup.
Use the bigger container for estimating the number of fry/fingerling at the time of transfer/harvesting/sale, etc.
Remember: Rough handling with hands cause problem for fry/fingerlings
3. Prophylactic measures to be taken up at the time of thinning/harvesting
Dip in 2% salt solution
Take 200 g of common salt in a bucket (10 lit capacity) and mix well till it dissolves. A piece of cloth or fine mesh net piece is placed in its central portion dipped in the salt water. Put the fry/fingerling in the cloth/net to have a dip for 30–40 seconds and lift with the net and release in the fresh water.
Instead of salt, a pinch of potassium permanganate also can be used.
4. Conditioning of fry/fingerling before transport
Net the pond, haul the stock, splash water for several minutes and release them back.
Take overnight soaked mustard oil cake @ 1 kg/decimal mix with water and apply throughout the pond after ½ hour of netting.
Repeat the same procedure on the following day.
Net the pond on the third day also, repeat the same treatment and apply overnight soaked mustard oil cake and Murate of potash (300 g MOC and 160 g M.P). Mix with water and apply uniformly throughout the pond.
On fourth day again net the pond, hold the fry/fingerling and splash water over this for half an hour. Spread the net and create flow of water from one end. Fry/fingerling will swim against the current and aggregated one should only be selected for transportation.
5. Transport of fish seed
Fish seed can be transported in Oxygen packed polyethylene bags and open container like barrel, aluminum hundies etc.
The carrying capacity of these container/polyethylene bag etc. depends upon:
Size and health condition of the seed
Distance and time to be taken
Water temperature
Supply of dissolved Oxygen
Usually 8000 to 10000 nos. of fry (10cm and 5cm respectively) can safely be transported in one barrel (200 lit) for 12–14 hours.
Take help of the following table for planning your fish seed transport for 5 to 6 hours.
| Size of fry | Types of packing material | |||
|---|---|---|---|---|
| Hundies (30 litre Capacity) | Barrels (200 litre Capacity) | |||
| Total | Per Litre | Total | Per Litre | |
| Spawn | 50,000 | 1,700 | -- | -- |
| Fry (1–2 cm.) | 3,000 | 100 | 20,000 | 100 |
| Fry (2–3 cm.) | 200 | 30 | 10,000 | 50 |
| Fingerling (10–15 cm.) | 100 | 3 | 1,400 | 7 |
6. Factors responsible for mortality
Presence of weed and predatory fishes
Presence of mollusc
Paucity of natural fish feed
Stocking of fish seed of different age and size group
Abrupt rise in water temperature in shallow ponds
Appearance of algal bloom by deep green colour of the water
Attack by predator like snakes, frogs, birds, otters, etc
Infestation by aquatic weeds
Predation by insects
Out break of disease
