Frozen Mysis Flat 454g

Mysis sits at the small end of the whole-animal frozen foods. At roughly 1 cm it is small enough to be swallowed whole by fish that cannot manage krill, and large enough to be worth chasing for fish that ignore fine powders.

• One ingredient – mysis and nothing else. No binder, no gelatin, no added colour, no vitamin premix.
• Whole animals of around 1 cm – small enough for seahorses and mandarins, which is the buying decision on this page.
• 11.1% crude protein as fed – approximately 69% on a dry-matter basis at 84.0% moisture.
• Whole-animal structure – the exoskeleton stays intact, giving the natural shape and movement in flow that triggers a feeding response in fish that ignore inert food.
• Both freshwater and marine – Ocean Nutrition lists mysis for carnivorous fish in both water types.
• 454 g flat pack – the bulk format, roughly four and a half times a 100 g blister.
• Accepted by newly imported fish – mysis is the conventional starting point when a fish has stopped eating, though nothing works every time.

Reproduced verbatim from Ocean Nutrition's published composition. Checked 7 August 2026.

Mysis

Allergen, additive and source notes

• Contains crustacean. That is the entire declaration – there are no other animal or plant sources in this product.
• No preservatives, antioxidants, added colours or vitamin premix are declared.
• Mysids are small shrimp-like crustaceans, not true shrimp, despite the common name "mysis shrimp".

Figures are as fed, on the frozen product, as published by Ocean Nutrition.

Ocean Nutrition's published directions are to feed two to five times a day, and to feed only the amount the fish will consume within five minutes.

• Snap a portion off the frozen slab and return the remainder to the freezer straight away.
• Thaw the portion in a small cup of tank water for a few minutes, then pour it through a fine net and rinse to keep the pack liquid out of the tank.
• Feed into flow. Mysis tumbling in a current reads as live prey, which is the whole reason it works on fish that refuse other foods.
• Remove anything uneaten after five minutes.

Feeding seahorses specifically

Seahorses feed slowly and repeatedly rather than in a rush, so they do better with several small feeds a day at the upper end of the two-to-five range. Target-feeding thawed mysis with a pipette or a feeding station keeps the food where the seahorse is, rather than letting flow carry it past faster tank mates.

Ocean Nutrition does not publish thawing directions for the flat pack format, so the method above is our own standard practice for whole-animal frozen foods rather than a manufacturer instruction.

Protein figures below are as fed, from each product's own published analysis.

Mysis and Krill Pacifica are the same format and the same pack weight. The 1 cm against 2.5 cm animal size is the only thing that should decide between them.

Suitable for

• Seahorses and pipefish, for which mysis is the conventional staple.
• Mandarins and dragonets being weaned off live pods onto prepared food.
• Small and medium marine community fish – clowns, cardinals, chromis, gobies, anthias, dottybacks and small wrasses.
• Freshwater carnivores including bettas, apistogramma, discus and smaller cichlids.
• Newly imported or off-food fish that have refused flake and pellet.

Not suitable for

• Strict herbivores as a diet. Tangs and rabbitfish will eat mysis, but they need the algae in Formula Two or a dried algae sheet.
• Large predators as a staple – a 1 cm item is inefficient for them. Use Krill Pacifica.
• A complete sole diet. A single-ingredient food carries no added vitamin or mineral premix, so rotate it with a formulated food.
• Filter-feeding corals and clams – still far too large a particle.
• Small tanks where 454 g will sit in the freezer for many months. The 100 g blister is the better format.

• Keep frozen in a domestic freezer. Reseal or bag an opened flat pack, as it picks up freezer burn faster than a sealed blister.
• Do not refreeze mysis that has fully thawed. Discard it.
• Snap portions while the slab is hard. Mysis that has softened and been refrozen fuses into a solid block and loses the loose whole-animal structure that makes it work.

• Frozen Krill Pacifica Flat 454g – the large-particle counterpart, so one freezer covers both ends of your stocking.
• Frozen Formula One 100g – a formulated diet with a full vitamin premix, to rotate against this single-ingredient food.
• Frozen Rotifers 100g – a step smaller again, for fry and for fish too small even for mysis.
• Frozen Artemia Brine Shrimp Flat 454g – a similarly sized alternative in the same flat pack format, useful for alternating.

Frozen foods are a consumable and carry no manufacturer warranty period. Your rights under the Australian Consumer Law apply in full and are in addition to anything stated here, including the guarantee that goods are of acceptable quality and fit for their stated purpose.

Frozen food is pick up only from our North Lakes store, because a pack that thaws on the way cannot be refrozen.

How big are the mysis in this pack?

Approximately 1 cm per animal. That is small enough for seahorses, mandarins and most small reef fish to swallow whole, and it is the main practical difference between this and Krill Pacifica at around 2.5 cm.

Is frozen mysis good for seahorses?

It is the conventional staple for captive-bred seahorses, and the 1 cm size suits them well. Feed several small portions across the day and target-feed rather than broadcasting, since seahorses feed slowly and lose out to faster tank mates.

Do I need to rinse frozen mysis before feeding?

Rinsing a thawed portion through a fine net removes the pack liquid and reduces the dissolved nutrient load entering the tank. Ocean Nutrition does not publish thawing directions for the flat pack, so treat this as good practice rather than a required step.

Can I feed mysis to freshwater fish?

Yes. Ocean Nutrition lists mysis for carnivorous fish in both freshwater and marine tanks, and bettas, apistogramma and discus take it readily.

Will mysis alone keep my fish healthy?

Not indefinitely. The declaration is a single ingredient with no added vitamin or mineral premix, so rotate it with a formulated food such as Formula One that carries a full premix.

Why does my fish eat mysis but refuse pellets?

Whole mysis keeps its shape and tumbles in flow, which reads as live prey to a fish that has not yet learned to recognise inert food. Many keepers use mysis as the bridge, then gradually mix in a pellet once the fish is feeding confidently.