# Growth Performance and Biochemical Profiles of Fairy Shrimp (Streptocephalus sirindhornae) Fed Natural Diets at Low and High Stocking Densities

## TL;DR

Fairy shrimp grow better at low densities and have high nutritional value when fed natural diets, making them useful for aquaculture.

## Contribution

The study reveals how rearing density and natural diets influence fairy shrimp growth and nutritional quality.

## Key findings

- Low-density rearing increases body weight and total length of fairy shrimp.
- Fairy shrimp prefer nutrient-rich algae and have high levels of essential amino acids and fatty acids.
- Natural diets with diverse plankton enhance the nutritional profile of fairy shrimp.

## Abstract

The fairy shrimp Streptocephalus sirindhornae is a small freshwater crustacean that can be used as natural live feed for fish and prawn farming. This study examined how rearing density and available food organisms affect its growth and nutritional quality. Lower densities reduced competition and water quality stress, allowing the shrimp to grow faster and reach larger sizes. Microscopic observation revealed that they mainly fed on green algae such as Chlorella sp. and Monoraphidium sp., which are rich in protein and pigments that promote growth. The fairy shrimp also contained high levels of essential amino acids, beneficial fatty acids, and carotenoids, indicating their high nutritional value. They selectively consumed algae species with higher nutrient content instead of all plankton available. These findings improve understanding of how fairy shrimp adapt their feeding behavior to their environment and provide useful insights for aquaculture management. Promoting the use of S. sirindhornae as live feed may support sustainable production of nutritious food for freshwater aquaculture species.

This study investigates the growth performance, gut content composition, and biochemical profiles of the fairy shrimp Streptocephalus sirindhornae cultured with natural diets under low and high stocking densities (20 and 40 ind. L−1). Fairy shrimp were reared for 15 days in 1 m3 floating cages placed in earthen ponds. On day 15, individuals in the low-density treatment exhibited significantly greater body weight (0.074 ± 0.013 g) and total length (20.97 ± 0.90 mm) than those in the high-density group. A total of 54 food taxa were identified in the gut contents, with phytoplankton comprising the dominant fraction (91%). In contrast, 105 food taxa were recorded in the culture ponds, including 54 phytoplankton and 51 zooplankton taxa; chlorophytes (27 taxa, 50%) and rotifers (33 species, 63.46%) were the most diverse groups. Fairy shrimp feeding on natural pond foods exhibited high levels of essential amino acids, with monounsaturated fatty acids dominating and linoleic acid (C18:2n6c) representing the principal polyunsaturated fatty acid. Overall, the results indicate that low-density rearing enhances fairy shrimp growth, while the high diversity of natural food organisms contributes to the favorable nutritional composition of S. sirindhornae.