The quality of feed used determines the profitability in fish farming. Protein digestibility is highly efficient in salmonids like trout and other salmonids that obtain protein in their diets mainly from fish source. They can obtain some of their energy from fats and, to some extent from carbohydrates.
Diet for different fish sizes:
– Alevins and fingerlings – need diets with at least 50% protein and 12-18% fat.
– For larger trout, the diet should have 38 45% protein and 16-18% fat.
Feed quality
Trout fish are highly carnivorous, voracious eaters & they prefer to feed on high proteineous diet.
Therefore, feed should contain high quality protein, fat, minerals, additives & micronutrients. These days feed manufacturers are giving emphasis on such high-quality feed.
Feeds with carotenoids pigments impart a pink or red colour to the flesh and do not affect fish health or growth rate. Pigmentation can be achieved in about 3 months when fish are actively growing, and in about 6 months in cold water.
Diets with Higher energy levels that help fish use protein more efficiently is available the feed manufacturer can provide the ratio of protein to energy in the high energy fish feed. For typical high energy diets the ratio should be about 20:1.
Feeding practices
body weight when compared to larger fish. Water temperature and fish size plays a crucial role in calculating the daily ration of trout feed. Due to faster metabolic rates in smaller fish they require more feed relative to their body weight when compared to larger fish.
Fish are poikilothermic (cold-blooded), water Temperature affects their body temperatures and metabolic rates. The nutrients loading of the water, coupled with the generally lower oxygen levels in warm water, can easily lead to oxygen deficit and respiratory distress.
In warm water, feeding rates should be monitored and kept at minimum levels to maintain good water quality and prevent wastage. It is always best to use a published feeding chart, usually provided by the feed manufacturer.
These charts are useful guides with specific adjustments to suit the farm conditions. Overfeeding will cause the fish to use the feed less efficiently with no increase in growth resulting in poor FCR. Therefore overfeeding & underfeeding should be avoided.
The stocking densities and size of fish along with water temperature in the farm will determine the appropriate feeding quantities. At water temperatures above 15°C, monthly sampling of the fish is recommended to adjust feeding percentages.
Bimonthly sampling is sufficient in cooler waters. Excess feed reduces water quality and promotes diseases in ponds.
How to feed trout
A high-quality feed is selected and the correct amount of feed is calculated following which the fish is fed in the most suitable way.
Trout will begin to feed within 15 days after hatching. Initially the alevin is fed by hand 12 15 times per day until all the fish are actively feeding.
| Fish size (g) | Stage | Growel Feed Pellet size (mm) | Feed specification (Protein/Lipid %) | Feeding frequency (times/day) | 4°C | 8°C | 12°C | 16°C | 20°C |
|---|---|---|---|---|---|---|---|---|---|
| 0.1 – 0.2 | Nursery | 0.3 | 52/12 | 8 – 12 | 1.9 | 3.3 | 4.2 | 4.8 | 3.4 |
| 0.2 – 0.5 | Nursery | 0.5 | 52/12 | 6 – 8 | 1.7 | 2.9 | 3.8 | 4.2 | 2.9 |
| 0.5 – 1.5 | Nursery | 0.8 | 52/12 | 4 – 6 | 1.5 | 2.6 | 3.2 | 3.5 | 2.5 |
| 1.5 – 8 | Early grower | 1.2 | 48/16 | 3 – 4 | 1.2 | 2.2 | 2.6 | 2.8 | 2.0 |
| 8 – 35 | Early grower | 1.8 | 48/16 | 2 – 3 | 1.0 | 1.8 | 2.1 | 2.3 | 1.7 |
| 35 – 150 | Grower | 3 | 45/18 | 1 – 2 | 0.7 | 1.3 | 1.7 | 1.9 | 1.4 |
| 150 – 500 | Grower | 6 | 45/18 | 1 – 2 | 0.5 | 0.9 | 1.3 | 1.6 | 1.1 |
(Feeding chart by ICAR-DCFR, Bhimtal)
Blogger:
Dr. Sathish Prasad
Senior Scientist – Aquatic Animal Health
Growel Innovation Center,
RS NO.57, Chevuru Village, Sriharipuram Panchayat, Mudinepalli Mandal, Krishna District – Andhra Pradesh India – 521329
Email: [email protected]