Fish Nutrition & Feed Technology

2. Nutrients and growth

Unit 2- Nutrients and growth

2.1.Nutrients and growth

The fish growth involves laying down of muscle, fat, epithelial and connective tissue. The growth in fish follows s-shaped curve. Initially, the fish growth will be slow due to the small size of fish and thus the difficulty in consuming more food. This phase is termed as preparatory phase. With the advancement of time fish starts to consume more food, grow bigger and their capacity to feed and grow increases. Beyond certain point, the rate of increase in growth begins to slow down as the total weight of fish has now increased to a maximum point and thus the growth now occurs at a diminishing rate. Although fish never stops growing but the growth is slower in older fish and proportional increase in size is greatest in younger fish.

Like any other terrestrial animal, fish also needs the same nutrients for their growth. However, the amount of these nutrients varies due to variation of metabolic rate. Hence supply of these nutrients is warranted in fish feed. Unlike animals, the availability of these nutrients to fish is different due to their surrounding environment. Some nutrients are available form water, which needs to be considered critically while formulating feed for fish.

Finfish require around 40 nutrients for optimal growth and well being. The proteins, lipids/fats and carbohydrates are considered as “macro nutrients”, while vitamins and minerals put together constitute “micronutrients” required for the healthy growth in fish.