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Discover Scuds

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Amphipods, also known as scuds, are small shrimp like crustations that have made their way into practically every aquatic environment there is. From the ocean to freshwater ponds, lakes, streams, caves, you name it! These little detritivores play a major role in the breakdown of dead organic material, especially plant detritus and leaf litter. By consuming this material, the scud frees up the locked away nutrients in the decaying plant which then become more accessible to other organisms in the food web.

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Not only do scuds do a great job at eating leftover fish food and filamentous algae, but like many small aquatic invertebrates they are a highly nutritious live food! Scuds reproduce quickly and can easily be cultured in a variety of separate containers to provide an endless live food source for many small to medium sized fish.

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Scuds typically live in the substrate of your aquarium but can regularly be seen swimming about and hanging out on the roots of floating plants, if there is cover or no fish in the system. They will establish a growing population in most fish tanks so long as they have the habitat to do so. An area of coarse gravel, seashells, live plants, leaf litter or other natural cover will make it easier for the scuds to find a safe home among hungry fish. Introducing them to the tank at night will also help them get to safety before they are gobbled up. You can easily make a separate scud tank to grow out the population, so you have a steady supply of live food for your fish. This can be done in a spare tank, storage tote or plastic trash can.

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Freshwater Scuds (Gammarus sp.) Care Sheet


Freshwater scuds are small crustaceans (typically 3–8mm) valued for their role in the aquarium as detritivores and a live food source. They’re easy to culture and thrive in both fish display tanks and dedicated breeding setups.

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Basic Information

  • Scientific name: Hyalella azteca

  • Common names: Scuds, amphipods, side-swimmers

  • Size: 3–8 mm

  • Lifespan: 10-12 months

  • Activity: active swimmers and crawlers when no predators are present

 

Tank Setup

  • Tank size: 5 gallon minimum (larger preferred for stability)

  • Substrate: gravel, sand, and leaf litter

  • Surface area: Leaf litter, sand, gravel, sponge filters, rocks

  • Filtration: Sponge filters are ideal — gentle and provide surface area

 

Water Parameters

  • Temp: 45-90°F They reproduce well at 68-86°F

  • PH: 7-8GH: 5-15 (our systems 10-15)

  • KH: 2-10 (our systems 5-8)

  • pH: 6.5-8

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Diet

  • Scuds are scavengers and detritivores:

  • Staples: Algae, decaying plant and animal matter, leaf litter, biofilm

  • Supplements: Blanched vegetables (zucchini, spinach), fish flakes, spirulina, pellets

  • Avoid overfeeding; scuds contribute to the cleanup crew but excess food can foul the water.

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Reproduction

  • Amphipods reproduce using a behavior called amplexus. In this process, a male grabs a female with his special front legs (called gnathopods) and holds her close to his underside. This can last from a couple of days or weeks, depending on the water temperature. It ends when the female sheds her outer shell, which means her eggs are ready to be fertilized.

  • Female amphipods have a brood pouch or marsupium, on their belly where they keep their eggs safe until they hatch. As the female gets older, she can carry more eggs. When the eggs hatch, the babies look like tiny adults—there’s no larval stage. 

  • Population control: Harvesting from breeding colony if no predators are present

 

Maintenance Tips

  • Do regular water changes (20–30% weekly) if you are feeding and growing a large population

  • Provide leaf litter for natural biofilm and shelter

  • Avoid medications with copper — lethal to inverts

  • Harvest from population as needed to avoid overcrowding

 

Pro Tips

  • As mentioned earlier, scuds are detritivores, meaning they feed on decaying organic matter and aren’t very picky eaters. They enjoy decomposing plant material, various types of algae, leaf litter, overripe fruits and vegetables, fish food, and more. While they usually leave live aquarium plants alone, a very large population with limited food may start to nibble on soft plants or moss. This is mostly a concern in tanks without fish. In aquariums that include fish, scud populations can't really get out of hand—in fact, they are a natural food source for the fish, helping both populations reach a healthy balance.

  • Store extras in a separate culture tub with crushed coral, leaf litter and aeration

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More to come! Thank you for your support!

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