ORNAMENTAL AQUACULTURE

A Revolution in Feeding Ornamental Fish: Mealworms and Microbes Pave the Way

Turkye, 24 January 2025 |

Guppies (Poecilia reticulata)

The dazzling colours of guppies gliding effortlessly through aquarium waters captivate enthusiasts worldwide. Yet, behind this visual splendour lies a challenge that stretches beyond aesthetics. The ornamental fish industry has long struggled to strike a balance—crafting sustainable yet nutritious diets that nurture the health of these aquatic gems while safeguarding the environment. Now, a pioneering study might just have found the answer.

Researchers in Turkey have turned to an unconventional source: yellow mealworms. Once seen as a promising alternative protein, these humble insect larvae are now making waves in aquaculture. But there’s an intriguing twist—before being fed to fish, the mealworms are fermented with beneficial bacteria, transforming them into a nutrient-rich superfood with health-boosting properties.

Published in the Turkish Journal of Agriculture - Food Science and Technology, the study focused on guppies (Poecilia reticulata), one of the most cherished ornamental fish. Over an 84-day period, researchers trialled diets enriched with mealworm larvae fermented using Lactobacillus plantarum and Lactobacillus brevis. The results were remarkable: guppies fed this innovative diet grew faster and developed healthier guts—crucial for their vibrant colours and overall resilience.

Feeding Fish with the Future in Mind

Ornamental aquaculture is no small industry. Aquariums adorn millions of homes, offering a glimpse into the underwater world. However, the feeds sustaining these fish often rely on unsustainable resources like fishmeal, harvested from depleting wild fish stocks.

Enter the yellow mealworm—a modest yet game-changing insect. Renowned for its high protein content and ability to thrive on organic waste, it offers an eco-friendly alternative to conventional feeds. However, raw mealworms have a drawback—their tough, chitin-rich shells are hard for fish to digest. Researchers tackled this issue through fermentation, a microbial process that breaks down complex components and unlocks hidden nutrients.

The fermentation process did more than enhance the mealworm’s nutritional value; it imbued the larvae with probiotics—beneficial bacteria that significantly improved the guppies’ gut health. These microbes played a transformative role in reshaping the fish’s intestinal microbiome, enabling better digestion and nutrient absorption.

A Glimpse Into Gut Microbiota

Larvas de gusano amarillo (Tenebrio molitor)

A healthy gut underpins the well-being of ornamental fish. The study revealed that guppies fed the fermented mealworm diet developed gut microbiota dominated by Proteobacteria, a bacterial group linked to improved digestion and immunity. In contrast, the control group exhibited less diverse microbiota, dominated by Fusobacteria.

This shift in gut microbiota is more than a scientific curiosity—it’s a revolution. A thriving gut ecosystem translates to better nutrient utilisation, faster growth, and enhanced immunity, all vital for ornamental fish celebrated for their beauty and vitality.

The physical changes were equally impressive. Guppies fed the fermented diet exhibited longer and broader villi—the tiny structures in the intestines responsible for nutrient absorption. This adaptation allowed the fish to maximise their intake of nutrients, fuelling growth and boosting their resilience.

From Aquariums to Ecosystems

The implications of this research extend far beyond this single study. In a world increasingly focused on sustainability, the ornamental aquaculture industry must evolve its practices. The fermentation of insect-based feeds offers a promising path forward, combining ecological responsibility with improved fish health.

Fermented mealworms address two critical concerns: reducing dependency on wild fish stocks and managing agricultural waste sustainably. Unlike traditional fishmeal, mealworms can be reared on by-products from farming, transforming potential waste into a valuable resource. Fermentation further amplifies this value, turning a sustainable feed into a nutritional powerhouse for ornamental fish.

A New Dawn for Ornamental Aquaculture

As aquarium enthusiasts seek more ethical and sustainable ways to enjoy their hobby, innovations like fermented mealworm feeds bring hope. These diets not only benefit fish farmers—who can rear healthier stock more efficiently—but also align with the values of environmentally-conscious consumers.

The shimmering guppy, a firm favourite among aquarists, could become the emblem of this transformation. The study’s findings show that a small dietary shift—introducing fermented mealworms—can profoundly impact growth, health, and resilience. It’s a powerful reminder that even the smallest creatures can drive significant change.

With continued research into this approach, the future of ornamental aquaculture appears brighter. Insects and microbes, it seems, may hold the key to preserving the aquatic beauty we cherish while protecting the planet we share.

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