Mysis Shrimp: A Favorite Fish & Coral Food

One of my favorite frozen foods to feed my saltwater fish is frozen mysis shrimp. Almost every fish I have ever kept has instantly recognized the floating white morsels as a meal. I’ve offered them at the same time as flakes (which would otherwise be voraciously eaten if it wasn’t competing with the mysis shrimps), and the fish will swim around the flakes to eat the apparently more tasty mysis.

That made me wonder why this food is so interesting to the fish—which made me wonder—what in the world are mysis shrimp, anyway?

Let’s take a closer look.

There are over 72 species of Mysids. Most of them are freshwater mysids, but there are marine species as well.
They are called “shrimps,” fairly casually, but taxonomists would not consider mysids to be true shrimps.

How is that for a fun trivia fact? Especially in a hobby full of people who enjoy using the scientific names of some species.

So the next time you want to impress your aquarium friends, be sure to let them know that mysis have a thoracic pouch (wasn’t that the name of the last movie in the Jurassic Park series?)

Sorry, that was silly–anyway, mysis shrimp have a thoracic pouch (not Jurassic pouch), and they don’t have a free-swimming larval phase.

Phew.

Glad we cleared that up.

Natural Habitat

Mysids naturally inhabit coastal zones across the high boreal and Arctic seas. They have also been found to inhabit freshwater northern lakes and the brackish waters of the Caspian Sea.

Some mysis shrimp species inhabit shallow waters in estuaries from the East Coast of Mexico to Florida, USA.

They are really hardy animals and can withstand a wide range of living conditions, changing temperatures, and salinities. Some species prefer the seabed, while others like to live in mid-water or among seagrass and algae.

Freshwater vs. Marine Mysis in the Hobby: Not all mysis shrimp sold for aquarium use are marine species. Some products are derived from freshwater species (such as Mysis relicta), while others are marine (like Mysidopsis spp.). For saltwater aquariums, marine mysis are generally preferred due to their better osmoregulation and nutritional profile for marine fish and corals. When purchasing mysis shrimp, check the packaging or product description to ensure you are selecting the appropriate type for your aquarium. Using freshwater mysis in a marine tank is not harmful in the short term, but marine species are typically a closer nutritional match for saltwater livestock.

What do Mysis shrimp eat?

Mysis shrimp are omnivorous and will feed on diatoms, plankton, and copepods. Some species will also eat detritus and algae, but since they are so small, it would take a tankful to make a meaningful contribution as members of the clean-up crew.

How diet affects nutritional value: The diet of mysis shrimp, especially when cultured, can significantly impact their nutritional content. Wild-caught mysis often have a more diverse gut content, while those raised in captivity may have a more limited diet. This is why some aquarists practice “gut-loading”—feeding mysis nutrient-rich foods (such as phytoplankton or high-quality microalgae) before offering them to fish. Gut-loaded mysis can provide additional vitamins and fatty acids to your aquarium inhabitants.

Choosing high-quality mysis: When selecting mysis shrimp as a food source, look for reputable brands known for clean processing and proper freezing. Avoid products with excessive debris or off-odors, which can indicate poor handling. If possible, choose mysis that have been gut-loaded or are labeled as high in omega-3 fatty acids for optimal fish health.

Behavior and Reproduction

Females carry developing young in a marsupium-like pouch at the base of their legs and can carry up to 30 fry, but the usual brood is 6 – 7 young at a time.

As soon as the fry are well developed, they are released into the water, and the female prepares her pouch by filling it with a new batch of eggs.

As these shrimp normally reach adult size (1 inch) in about 3 weeks, this leads to a new generation being created every 30 days.

Use as fish food

Mysis shrimp are a popular food for both marine fish and corals, prized for their high palatability and nutritional value. But what makes them such a high-quality food, and how do they compare to other options?

Nutritional Profile of Mysis Shrimp

Mysis shrimp are rich in protein (typically 60–70% dry weight), moderate in fat, and contain beneficial omega-3 fatty acids such as EPA and DHA. This makes them an excellent energy source for active marine fish and helps support vibrant coloration and healthy immune systems. Their soft exoskeleton is easily digested by most aquarium species, and their size is suitable for a wide range of fish, from small gobies to larger wrasses and angelfish. Corals and other filter feeders will also readily consume finely chopped or blended mysis.

Comparison to Other Foods

• Brine shrimp: While brine shrimp are widely available and eagerly eaten, they are lower in protein and essential fatty acids compared to mysis. Unless gut-loaded, brine shrimp are less nutritious and best used as an occasional treat.
• Flakes and pellets: These can provide a balanced diet if formulated well, but many fish find mysis more palatable and may show improved color and activity when offered as a supplement.
• Other frozen foods: Mysis are generally superior in nutrition to most single-ingredient frozen foods, but variety is still important for long-term health.

Potential Drawbacks and Feeding Tips

• Risk of over-reliance: Feeding only mysis can lead to nutritional imbalances, such as fatty liver disease, especially in species that require more fiber or plant matter. Always offer a varied diet, including algae-based foods and other protein sources.
• Phosphate and nutrient input: Frozen mysis can release excess nutrients into your tank. Rinse frozen mysis in a fine mesh strainer with RO/DI water before feeding to reduce phosphate and unwanted organics.
• Portion control: Feed only what your fish will consume within a few minutes to avoid water quality issues.
• Suitability: Mysis are appropriate for most marine fish, invertebrates, and corals, but very small fish or fry may require smaller foods such as rotifers or copepods.

Freeze-Dried and Live Options

Mysis shrimp are also available as a freeze-dried product, which offers convenience and a long shelf life. However, freeze-dried foods should be rehydrated before feeding to prevent digestive issues. Live mysis are sometimes available and are especially useful for finicky or wild-caught fish that may not accept prepared foods.

Culturing Mysis Shrimp at Home

Mysis shrimp are aquacultured—so it is possible to grow your own food. Culturing mysis at home can provide a continuous supply of live, highly nutritious food, but it requires careful planning and maintenance.

• Basic requirements: A dedicated tank (typically 10–20 gallons or larger), stable water parameters (marine or brackish, depending on species), gentle filtration (such as sponge filters), and regular feeding with live or prepared microfoods (e.g., phytoplankton, copepods, fine particulate foods).
• Common challenges: Mysis shrimp are cannibalistic—adults will eat their young if not separated, and may even prey on other adults if the population density is too high. To minimize losses, provide plenty of hiding spaces (such as mesh or coarse sponge), use refugia or mesh barriers to separate juveniles from adults, and harvest regularly to keep densities manageable. Maintaining water quality is also critical, as uneaten food and waste can quickly degrade conditions.
• Benefits and drawbacks: Home culturing allows you to gut-load mysis with high-quality foods, ensuring optimal nutrition for your fish. However, it is labor-intensive, requires space and equipment, and is prone to crashes if cannibalism or water quality issues are not managed. For most hobbyists, the convenience of frozen or freeze-dried mysis is hard to beat, but culturing may be worthwhile if you are breeding sensitive species or need live food for finicky eaters.

A few questions for you:

Have you ever fed mysis shrimp to your fish? Live or frozen? If frozen—do you prefer the cubes or flat packs?