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What Do Shrimp Eat? Slime, Soft Algae, Parasites, and Their Own Old Shells

Shrimp eat biofilm, soft algae, decaying plants, and their own shed shells. Here's what to feed them in a home tank and how much.

Jack·6 min read·May 21, 2021·Updated October 13, 2026

If you've watched a shrimp in an aquarium, you've seen it pick at a bare rock or leaf with tiny claws, as if it were eating nothing. It is eating. That rock is coated in biofilm, a thin living film of microbes, and for many freshwater shrimp it is most of what they eat. Shrimp are omnivores. They also eat soft algae, decaying plants, detritus, and small animals. Some eat parasites picked off fish. Nearly all of them eat their own shed shells, and sometimes each other.

The meal you can't see

Pet-store favorites like Cherry and Bee shrimp eat algae wafers, pollen, and snowflake pellets when you offer them. In nature they graze. Shrimp Science says biofilm "makes up the vast majority of their natural diet." Decaying plant matter makes up much of the rest.

This changes how to think about a shrimp tank. A brand-new, spotless aquarium has little biofilm on its surfaces, so it holds little food. An older tank, with years of film on its rocks, glass, wood, and leaves, feeds shrimp around the clock.

Not quite a vacuum cleaner

Shrimp are often sold as a cleanup crew, and that claim goes too far. Freshwater shrimp eat only a few kinds of algae, mostly the soft ones, and Shrimp Science warns against relying on them to fix an algae outbreak.

Many keepers say shrimp leave healthy live plants alone. That is a common belief, but it isn't well documented. What is clear is that shrimp spend much of their time grazing the biofilm on plant leaves, and they readily eat plant matter once it starts to decay.

What wild shrimp eat

Out of the aquarium, shrimp eat more meat than their gentle reputation suggests. The white shrimp (Litopenaeus setiferus), one of the species sold as seafood, eats different food at different ages. Its larvae drift and feed on zooplankton and phytoplankton. Juveniles and adults feed on detritus, plants, microorganisms, small invertebrates, and even small fish.

Brown shrimp shift their diet as they grow from juvenile to subadult. They eat more detritus and more bottom-dwelling animals, such as polychaete worms and amphipods.

Hobbyist guides describe shrimp in general as scavengers of detritus, decaying plants, and small invertebrates, and some will eat dead animals. Live fish and insects are not a documented staple. A small, weak, or dead animal is a meal. A healthy fish usually is not.

Cleaner shrimp: parasites on the menu

A few marine shrimp have turned scavenging into a service. Cleaner shrimp come from several unrelated groups, including Lysmata, Urocaridella, and Periclimenes. They set up "cleaning stations" where fish come to have parasites removed.

Their appetite reaches beyond the fish themselves. In a 2015 PLoS ONE study, Militz and Hutson found that the cleaner shrimp Lysmata amboinensis also ate parasite eggs and larvae from the surrounding water. In 12-hour daytime trials, the shrimp ate about 63% of parasite eggs and 26% of free-swimming larvae. At night they ate only about 14% of the eggs. Fish kept with the shrimp had roughly half the parasite infection success of fish kept without them.

Cleaner shrimp do sometimes enter a predator's mouth. A 1982 study reported Lysmata seticaudata cleaning a moray eel in the Mediterranean. In 2024, researchers in Moorea, French Polynesia, saw an Urocaridella cleaner shrimp enter a giant moray's mouth three times.

These shrimp are not reckless. A 2019 Biology Letters paper by Caves, Chen, and Johnsen found that L. amboinensis behaves differently depending on whether its client fish is a predator. The shrimp weighs the risk before it goes in.

Cleaning is also not their whole diet. Cleaner shrimp take other food as well. One public aquarium says most of a cleaner's nutrients come from cleaning fish, but that is a general claim rather than a measured one.

Shells, molting, and cannibalism

A shrimp grows by shedding its hard exoskeleton and forming a new one. After a molt, the shrimp is soft and essentially defenseless for several hours while the new shell hardens. Hobbyist sources say molting shrimp often hide for a few days.

The old shell doesn't go to waste. Shrimp eat their shed shells to recover the calcium in them, so it is best to leave molts in the tank.

The soft stage is also when shrimp are most likely to be eaten by other shrimp. The risk depends heavily on conditions. Cannibalism rises when shrimp are crowded and when food is scarce, and shrimp farming guidance says to keep feed plentiful during mass molts. In other words, well-fed shrimp with room to spread out are far less likely to eat each other.

Feeding shrimp in a home tank

Everything above points to the same rule: feed the shrimp, but feed them lightly.

  • How often: Most keepers feed every day or every two to three days. A well-aged tank with plenty of biofilm and algae may need food only every few days.
  • How much: Start small. Give only what the shrimp finish within two to three hours, and remove leftovers after a couple of hours. Uneaten food breaks down into ammonia, which stresses shrimp.
  • Vegetables: Broccoli, carrots, cucumber, kale, lettuce, peas, spinach, sweet potato, and zucchini are all safe. Use organic or home-grown produce to avoid pesticide residue.
  • Grow their natural food: Letting a new tank age builds biofilm. Indian almond leaves, leaf litter, and biofilm-promoting powders can help.
  • Protein and calcium: Both support shell growth after each molt. This is another reason to leave shed shells in place.

What to keep away from shrimp

Copper is the main danger, but where it comes from matters. Trace amounts in shrimp foods and plant fertilizers are usually harmless. Some makers add copper on purpose, because shrimp use it in their blood. The real risk is copper-based fish medication. Practical Fishkeeping advises against medicating a tank that holds dwarf shrimp.

Copper can also affect how shrimp find food. A 2025 study of the wild freshwater shrimp Caridina multidentata measured a lethal copper concentration (LC50) of 1.15 mg/L. Shrimp exposed beforehand to lower, non-lethal levels were worse at detecting food odors.

Finally, never release aquarium shrimp outdoors. In Texas, for example, Parks and Wildlife Code §66.007 bars importing, possessing, selling, or releasing exotic fish or shellfish classed as harmful or potentially harmful without state authorization. Check your state's current prohibited list before you buy an unusual species.

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