Study supports insect- and algae-based trout feeds as practical options

Version 1 — Brief

A new Animals study reports that practical, lower-footprint aquafeeds built with insect meal, microalgae-derived omega-3s, plant proteins, single-cell ingredients, and aquaculture by-products supported rainbow trout growth, nutrient retention, body composition, and flesh quality at levels comparable to a conventional feed. The trial compared a standard control diet with three alternative formulations — No-PAP, PAP, and Mix — and found the eco-efficient diets met key production and product-quality benchmarks in Oncorhynchus mykiss. The work fits with a broader run of trout research showing that insect meals can replace a meaningful share of fishmeal without hurting growth, while DHA-rich microalgae such as Schizochytrium can help replace fish oil and maintain long-chain omega-3 supply. It also aligns with by-product work in other species: in juvenile yellowtail, a 6-week Animals trial found that replacing up to 35% of fishmeal protein with shark by-product-based composite mixtures maintained growth and survival, although some formulations lowered EPA and DHA levels. (mdpi.com)

Why it matters: For veterinary professionals working in aquaculture, the finding adds to evidence that feed reformulation can move beyond proof-of-concept and toward commercially practical diets without obvious tradeoffs in fish performance or fillet quality. That matters as producers face ongoing pressure to reduce dependence on marine ingredients; IFFO says global fishmeal production for 2025 is projected at about 5.6 million tons, with fish oil at roughly 1.2 million to 1.3 million tons, underscoring why alternative proteins and lipids remain strategically important. At the same time, the yellowtail data are a useful reminder that replacing fishmeal with by-product blends may preserve growth while still shifting fatty-acid profiles, so formulation targets need to include product quality as well as biomass gain. In Europe, insect processed animal proteins have already been authorized for aquaculture feeds, which gives this line of research a clearer regulatory path than it had a decade ago. (iffo.com)

What to watch: The next question is whether these formulations hold up on economics, ingredient availability, farm-scale performance, and fatty-acid outcomes, not just in controlled feeding trials. (mdpi.com)