Commercial fish feeds are manufactured as either extruded (floating or buoyant) or pressure-pelleted (sinking) feeds. Both floating and sinking feed can produce satisfactory growth, but some fish species prefer floating, others sinking. Shrimp, for example, will not accept floating fed, but most fish species can be trained to accept a floating pellet.

Extruded feeds are more expensive due to the higher manufacturing costs. Usually it is advantageous to feed a floating (extruded) feed. This enables the farmer can directly the feeding intensity of his fish and adjust feeding rates accordingly as this is an important management strategy in ensuring maximum fish growth and feed use efficiency.

As earlier said manufactured feeds are available in variety of sizes ranging from fine crumbles for small fish (fry, swim-up frys) to large sizes. The pellet size should be approximately 20-30% of the size of the fish species mouth gape. Feeding too small a pellet results in inefficient
feeding and feed utilizations because more energy is used in finding and eating more pellets.

Conversely, pellets that are too large for fish mouth will depress feeding and, in the extreme, cause choking. Therefore the appropriate feed size for the right fish to eat and the fish will actively eat.

Read Also: Fish Nutrition, Feeds and Feeding

Types of Fish Feed

Fish feed plays a crucial role in aquaculture, providing essential nutrients for fish growth, health, and sustainability. There are various types of fish feed formulated to meet the dietary needs of different fish species at various stages of their lifecycle. Understanding the types of fish feed available can help optimize aquaculture practices for better fish health and production.

The following are the different types of fish feed;

1. Pelleted Fish Feed

Pelleted fish feed is one of the most common types used in aquaculture. It consists of compressed and compacted pellets made from a mixture of ingredients such as fish meal, soybean meal, grains, vitamins, and minerals.

These pellets are designed to float or sink, depending on the feeding habits of the fish species. Pelleted feed is convenient to store, handle, and distribute, making it ideal for commercial fish farming operations.

2. Extruded Fish Feed

Extruded fish feed undergoes a cooking process where raw ingredients are pushed through a machine under high pressure and temperature. This process gelatinizes the starches and proteins, improving digestibility and nutrient absorption for fish. Extruded feed pellets are durable and stable in water, making them suitable for both freshwater and marine fish species.

3. Powdered Fish Feed

Powdered fish feed consists of finely ground ingredients, providing a high surface area for quick digestion. It is often used for feeding larval and juvenile fish that require small, easily digestible particles. Powdered feed formulations are rich in proteins, vitamins, and minerals essential for the early growth stages of fish.

4. Live Feed

Live feed includes organisms such as brine shrimp, daphnia, and rotifers, which are cultured and fed to fish larvae and fry. These live organisms provide natural nutrition and stimulate predatory behavior in fish, enhancing growth and survival rates. Live feed is particularly crucial in hatcheries and nurseries where small fish require specific nutrients and feeding behaviors.

5. Gel-based Feed

Gel-based fish feed is a semi-solid formulation that can be molded into various shapes and sizes. It typically contains a mix of proteins, carbohydrates, and vitamins suspended in a gel matrix. Gel-based feed is beneficial for feeding finicky or herbivorous fish species that prefer softer textures and slower feeding rates.

Benefits of Different Fish Feeds

Nutrient Balance: Each type of fish feed is formulated to provide a balanced mix of proteins, fats, carbohydrates, vitamins, and minerals tailored to the nutritional requirements of specific fish species.

Digestibility: Pelleted and extruded feeds undergo processing that enhances digestibility, ensuring efficient nutrient absorption and minimizing waste.

Growth and Development: Properly formulated fish feeds promote healthy growth, development, and reproductive performance in fish, contributing to sustainable aquaculture practices.

Example of Usage in Aquaculture

In salmon farming, for example, pelleted fish feed containing high-quality proteins and omega-3 fatty acids is crucial for promoting rapid growth and enhancing the nutritional profile of farmed salmon. The pellets are formulated to float on the water surface, allowing easy monitoring of feeding behavior and minimizing environmental impact.

Therefore, understanding the types of fish feed available and their benefits is essential for optimizing aquaculture practices and ensuring the health and productivity of farmed fish, and by selecting the right fish feed type based on species, growth stage, and environmental conditions, aquaculturists can support sustainable fish farming and meet global demand for high-quality seafood.

Feeding Rate, Frequency and Timing

Types of Fish Feed and Best Feeding Methods

The most important rule in fish nutrition is to avoid overfeeding. Overfeeding is a waste of expensive feed. It is also results in water pollution, low dissolved oxygen levels, increased biological oxygen demand, and increased bacterial loads.

Usually, fish should be fed only the amount of feed that they can consume quickly (less than 25 minutes). Many growers use floating (extruded) feeds in order to observe feeding activity and to help judge ifmore or less should be fed.

Even with careful management, some feed ends up as waste. For example, out of 100 units of feed fed to fish, typically about 10 units of feed are uneaten (wasted) and 10 units of sold and 30 units of liquid wastes (50% total wastes) are produced by fish.

Of the remaining feed, about 25% is used for growth and another 25% is used for metabolism (heat energy for life processes). These numbers may vary greatly with species, sizes, activity, water temperature, and other environmental conditions.

Feeding rates and frequencies are in part a function of fish size. Small larval fish and fry need to be fed a high protein diet frequently and usually in excess. Small fish have a high energy demand and must eat nearly continuously and be fed almost hourly.

Feeding small fish in excess is not as much of a problem as overfeeding larger fish because small fish require only a small amount of fed relative to the volume of water in the culture system.

As fish grow, feeding rates and frequencies should be lowered, and protein content reduced. However, rather than switching to a lower protein diet, feeding less allows the grower to use the same feed (protein level) throughout the grow-out period, thereby simplifying feed inventory and storage.

Feeding fish is labour-intensive and expensive. Feeding frequency is dependent on labour availability, farm size, and the fish species grown. Large catfish farms with many ponds usually feed only once per day because of time and labour limitations, while smaller farms may feed twice per day.

Generally, growth and feed conversion increase with feeding frequency. In indoor, intensive fish culture systems, fish may be fed as many as 5 times per day in order to maximum growth at optimum temperatures.

Feed acceptability, palatability and digestibility vary with the ingredients and feed quality. Fish framers pay careful attention to feeding activity in order to help determine feed acceptance, calculate feed conversion ratios and feed efficiencies, monitor feed costs, and track feed demand throughout the year. Recommended framed fish feeding rate is between 1-4% of their body weight per day.