No, you should not use the commercial form of baking yeast in fish feed. Baking yeast is not designed to be used as a food source for fish and could be harmful to their health. It is important to use a fish feed that is specifically designed for fish and is formulated to meet their nutritional needs.

Some dried yeast products have added osmoprotectants (usually sugars or glycerol) which often add no added nutritional value to fish and could encourage unwanted bacterial species. Overall fresh dried yeast is a good source for amino acids, trace elements, B vitamins and Vitamin C. It is not a balanced diet however so should be supplemented with unsaturated fatty acids (corn cob and linseed/flax are popular sources), additional cheaper protein (usually soya) and other vitamin sources.

Yeast extract is yeast that has undergone autolysis resulting in a breakdown of proteins into free amino acids. Otherwise there is little difference in nutritional value.

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Commercial baking yeast shouldn't be used in fish feed since it might not meet the nutritional needs of fish and might not produce the best results. Commercial baking yeast is primarily designed for baking and may not offer the proper mix of nutrients for fish, which have distinct dietary requirements.

Fish feed formulations are made precisely to fulfil the nutritional needs of different fish species, taking into account things like their size, age, and developmental stage as well as their natural diet in the wild. Fish need a specific combination of proteins, fats, carbs, vitamins, and minerals in their food to grow and thrive.

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