Sustainable Fish Feed: Can Vegetable-Based Diets Replace Fish Meal?

Nico Varela in Climate & Environment December 2025 • 5 min read.

"Exploring the Potential of Extrusion Technology to Create Nutritious and Environmentally Friendly Fish Feed"

Aquaculture, the farming of aquatic organisms, is a rapidly growing industry crucial for meeting the increasing global demand for seafood. Traditional fish feed relies heavily on fish meal, a product derived from wild-caught fish. However, the use of fish meal raises sustainability concerns due to its impact on marine ecosystems and the finite nature of fish stocks. As a result, researchers and producers are actively seeking alternative, more sustainable ingredients for fish feed.

Vegetable-based diets have emerged as a promising alternative to fish meal. They offer a readily available and potentially more environmentally friendly source of nutrients for farmed fish. However, simply replacing fish meal with vegetable matter isn't enough. The nutritional composition and physical properties of the feed must be carefully optimized to ensure the fish receive adequate nutrition and the feed is palatable and digestible.

This article explores the optimization of single-screw extrusion process for producing fish feeds based on vegetable meals. Extrusion technology offers a means to transform raw vegetable ingredients into a palatable, digestible, and nutritionally balanced feed. Moreover, we’ll examine the nutritional effects of these extruded vegetable-based feeds on juvenile pacu, a commercially important fish species in South America, providing a case study for the potential of this approach.

Extrusion: The Key to Unlocking Vegetable-Based Fish Feed

Fish swimming through vegetable gardens, representing sustainable fish feed.

Extrusion is a process where raw materials are forced through a die under pressure and heat. In the context of fish feed, extrusion cooking offers several advantages. It can improve the digestibility of vegetable proteins, enhance the palatability of the feed, and create a product with desirable physical characteristics, such as buoyancy and water stability. The research optimizes this process to create fish feed using corn meal, soybean meal, and bovine plasma protein concentrate. The aim was to maximize expansion and floatability while minimizing bulk density and water solubility.

The researchers used a single-screw extruder and carefully controlled factors like blend moisture and extrusion temperature. By varying these parameters, they investigated how they affected the final product's expansion, bulk density, water absorption index (WAI), water solubility index (WSI), and floatability. Here's a summary of what they found:

Expansion: Higher expansion was achieved at intermediate temperatures and low moisture levels.
Bulk Density: The lowest bulk density was observed at specific temperature and moisture combinations, indicating a more porous and digestible feed.
Water Absorption Index (WAI): WAI increased with temperature up to a certain point and decreased with higher moisture content.
Water Solubility Index (WSI): WSI was inversely related to moisture content.
Floatability: Maximum floatability was achieved at intermediate temperature and moisture levels.

Through careful manipulation of the extrusion process, the researchers were able to create a vegetable-based fish feed with physical properties comparable to traditional fish meal-based feeds. This is a crucial step in making vegetable-based diets a viable alternative for aquaculture.

The Future of Fish Farming: Sustainable and Nutritious

This research demonstrates that vegetable-based diets can effectively replace fish meal in aquaculture, offering a more sustainable and environmentally responsible approach to fish farming. By optimizing the extrusion process, it's possible to create feeds that not only meet the nutritional needs of farmed fish but also possess desirable physical properties for efficient feeding and reduced waste.

While this study focused on pacu, the principles and techniques can be applied to other commercially important fish species. Further research is needed to fine-tune the formulations and extrusion parameters for different fish types and to assess the long-term effects of vegetable-based diets on fish health and welfare.

The transition to sustainable fish feed is essential for the long-term viability of the aquaculture industry and the health of our oceans. By embracing innovative technologies and exploring alternative ingredients, we can ensure a future where fish farming contributes to, rather than detracts from, the sustainability of our planet's ecosystems.

About this Article -

This article was crafted using a human-AI hybrid and collaborative approach. AI assisted our team with initial drafting, research insights, identifying key questions, and image generation. Our human editors guided topic selection, defined the angle, structured the content, ensured factual accuracy and relevance, refined the tone, and conducted thorough editing to deliver helpful, high-quality information.See our About page for more information.

This article is based on research published under:

DOI-LINK: 10.1016/j.anifeedsci.2017.09.004, Alternate LINK

Title: Optimization Of Single Screw Extrusion Process For Producing Fish Feeds Based On Vegetable Meals And Evaluation Of Nutritional Effects Using A Juvenile Piaractus Mesopotamicus Model

Subject: Animal Science and Zoology

Journal: Animal Feed Science and Technology

Publisher: Elsevier BV

Authors: Raúl E. Cian, Carla Bacchetta, Jimena Cazenave, Silvina R. Drago

Published: 2017-12-01

Everything You Need To Know

Why is there a growing interest in finding alternatives to traditional fish feed?

Traditional fish feed relies heavily on fish meal, which is derived from wild-caught fish. This dependence raises sustainability concerns due to its impact on marine ecosystems and the limited availability of fish stocks. The move towards vegetable-based diets aims to address these concerns by providing a more sustainable and environmentally friendly alternative source of nutrients for farmed fish, reducing the reliance on ocean resources.

How does extrusion technology play a role in creating effective vegetable-based fish feed?

Extrusion technology involves forcing raw materials through a die under pressure and heat. In creating vegetable-based fish feed, the single-screw extrusion process enhances digestibility of vegetable proteins, increases the feed's palatability, and ensures the product has desirable physical characteristics like buoyancy and water stability. By carefully controlling blend moisture and extrusion temperature, the process can be optimized to produce high-quality, sustainable fish feed.

What specific effects do temperature and moisture levels have on the physical properties of extruded fish feed?

The research findings highlight specific effects of the extrusion process parameters on the feed's properties. Higher expansion was achieved at intermediate temperatures and low moisture levels, while the lowest bulk density occurred at specific temperature and moisture combinations. The Water Absorption Index (WAI) increased with temperature up to a certain point and decreased with higher moisture content, whereas the Water Solubility Index (WSI) was inversely related to moisture content. Maximum floatability was observed at intermediate temperature and moisture levels. These insights are critical for tailoring the extrusion process to create optimal fish feed.

What makes juvenile pacu a relevant subject for studying the effectiveness of vegetable-based fish feed?

The study focused on juvenile pacu, a commercially important fish species in South America. By examining the nutritional effects of extruded vegetable-based feeds on pacu, the research provided a concrete case study illustrating the potential of vegetable-based diets to replace traditional fish meal. This approach ensures that farmed fish receive adequate nutrition and the feed is both palatable and digestible, supporting the healthy growth of the fish. While the study focused on Pacu, this process and design could be applied to a variety of other fish species.

What are the broader implications of using vegetable-based diets in aquaculture for the sustainability of fish farming?

By successfully optimizing the extrusion process for vegetable-based fish feed, this innovation paves the way for a more sustainable and environmentally responsible approach to aquaculture. Replacing fish meal with vegetable-based diets reduces the pressure on marine ecosystems and lowers the environmental footprint of fish farming. This shift ensures that the nutritional needs of farmed fish are met while promoting efficient feeding practices and minimizing waste, contributing to a more sustainable future for the fish farming industry.