Pygmy hatchetfish with shrimp

By the Shrimp Tank Hub editorsUpdated Oct 27, 2026Research-based

The pygmy hatchetfish (Carnegiella myersi) is the smallest and most delicate hatchetfish, with a shallower keel than its relatives that gives it a longer, slimmer look (Seriously Fish). It comes from small, shaded forest streams in the Peruvian Amazon, with a second population in Bolivia (Seriously Fish). Maidenhead Aquatics calls it a surface-hugging blackwater species and notes it has not been bred in home aquariums, so the fish for sale are wild-caught. Its bigger cousin is covered in marbled hatchetfish with shrimp.

Pygmy hatchetfish at a glance

Will pygmy hatchetfish eat shrimp?

• Adult shrimp: no realistic risk, in our reading. A 1-inch fish that feeds on small insects at the surface (Seriously Fish) is not a threat to grown shrimp on the bottom. None of the sources we checked rates pygmy hatchetfish for shrimp safety directly, so this is our assessment.
• Shrimplets: low risk, not zero. Baby shrimp mostly stay on moss and the substrate, but Practical Fishkeeping warns that almost any active fish will treat a hatchling shrimp as food if it gets the chance (our reading for a surface feeder).
• Eggs and berried females: safe. Shrimp carry their eggs under the tail.

For other fish that stay near the top, see Norman's lampeyes with shrimp and clown killifish with shrimp, or the full cherry shrimp tank mates list.

Matching the water

Seriously Fish lists 73–79 °F, pH 4.0–7.0 and 1–6 dGH, and Maidenhead Aquatics lists 23–27 °C and pH 4.5–7.0. Cherry-type shrimp tolerate 65–85 °F, pH 6.2–8.0 and GH 4–8 (The Shrimp Farm). By our comparison:

• With cherry shrimp: about 74–78 °F, pH 6.5–7.0 and GH 4–6 sits inside both ranges. Hard, alkaline tap water above pH 7 is outside the fish's listed range.
• With crystal and other Caridina: the soft, acidic water suits both, but crystal reds prefer about 68–74 °F (see crystal red shrimp care). That only overlaps the cool end of the hatchetfish's range, so it's a compromise.

Maidenhead Aquatics says hatchetfish are sensitive to rising nitrate and swings in water chemistry, so test often and change water in small, matched amounts. See shrimp tank pH, GH and KH explained and shrimp tank water changes.

Tank size and setup

• Lid first: Seriously Fish says the top must be well covered because these fish jump, even when you slide the lid open to feed. Maidenhead Aquatics says to block gaps around equipment with filter sponge, and Aquarium Co-Op says hatchetfish will escape through the narrowest slot. See do shrimp need a lid.
• Surface area: at least 20 × 12 in (Seriously Fish).
• Floating plants with open water: Seriously Fish wants floating plants but some clear surface for swimming, plus driftwood and leaf litter, which also feeds shrimp biofilm (our note). See best plants for a shrimp tank and driftwood and botanicals for shrimp.
• Very gentle flow, dim light: water movement should be minimal and lighting not bright (Seriously Fish). A sponge filter suits both; see shrimp-safe filters.
• Mature tank: Seriously Fish and Maidenhead Aquatics both want a well-matured tank. See how to cycle a shrimp tank.

Keep a real school

Seriously Fish says six should be the minimum, with more if possible. Maidenhead Aquatics says they gather in large numbers in nature and do better at 10 or more. They can share the tank with other Carnegiella hatchetfish (Seriously Fish).

Other good tankmates

Seriously Fish says this is not a general community fish: keep it with similar-sized, peaceful characins and small catfish, and no active tankmates. Maidenhead Aquatics suggests small peaceful tetras, pencilfish, corydoras and small suckermouth catfish. It also lists dwarf cichlids, but Aquarium Co-Op warns that dwarf cichlids go after shrimp. See green neon tetras with shrimp, dwarf pencilfish with shrimp and pygmy corydoras with shrimp.

Feeding both

Pygmy hatchetfish eat small insects at the surface in the wild and take floating foods such as flake, micro pellets, small dried insects and bloodworm; wingless fruit flies make a good live treat (Seriously Fish). Aquarium Co-Op says underfeeding is a common problem because hatchetfish don't like to swim down for sinking food. The upside for a shrimp tank is that sinking shrimp food goes straight past them (our note). See best shrimp food and what do shrimp eat.

Quarantine matters more than usual

Aquarium Co-Op says most hatchetfish are wild-caught and may reach stores underfed and weak, and recommends always quarantining them, watching them eat before you buy, and treating for ich and internal parasites. Many of those medications should never go into a shrimp tank (Practical Fishkeeping), so finish treatment in a separate tank before the fish meet your shrimp.

How to add pygmy hatchetfish to a shrimp tank

• Shrimp first. Let the colony settle before adding fish (Practical Fishkeeping).
• Acclimate slowly and keep the lights low the first day (our suggestion). See how to drip acclimate.
• Check the lid before the fish go in.
• Quarantine the fish separately. Practical Fishkeeping says many fish medications are not safe for invertebrates. If fish get sick, ask a fish veterinarian or an experienced store about treatment that won't harm the shrimp. See how to quarantine and is copper toxic to shrimp.

Common mistakes

• Gaps in the lid around filters and heaters.
• Strong surface flow from the filter.
• Feeding only sinking food.
• Adding fish straight from the store without quarantine.

Track it

Log temperature, pH, GH and TDS on the free Water Parameter Log printable so you can keep the tank in the range both species share.

Frequently asked questions

Will pygmy hatchetfish eat cherry shrimp?

Not adults, in our reading. They are about 1 inch long and feed at the surface (Seriously Fish). A shrimplet that swims up into open water could be eaten.

What is the difference between pygmy and marbled hatchetfish?

The pygmy hatchetfish (Carnegiella myersi) is the smallest hatchetfish, about 1 inch, with a shallower keel; the marbled hatchetfish (C. strigata) is about 1.4 inches with marbled bands (Seriously Fish).

What water do pygmy hatchetfish need?

Seriously Fish lists 73 to 79 °F, pH 4.0 to 7.0 and 1 to 6 dGH. With cherry shrimp, aim for about 74 to 78 °F and pH 6.5 to 7.0.

How many pygmy hatchetfish should I keep?

At least 6 (Seriously Fish); 10 or more is better (Maidenhead Aquatics).

Do pygmy hatchetfish need a lid?

Yes. Seriously Fish says they jump readily, even when the lid is slid open for feeding.

What do pygmy hatchetfish eat?

Floating foods such as flake, micro pellets, small dried insects and bloodworm, with wingless fruit flies as a treat (Seriously Fish).

Sources: Seriously Fish, Carnegiella myersi (pygmy hatchetfish) (smallest and most delicate hatchetfish, shallow keel; Peruvian Amazon near Yurimaguas plus Bolivia; small shaded forest streams; 25 mm SL; surface at least 50 × 30 cm; well-matured tank, floating plants with open surface, minimal flow, dim light, well-covered top, jumps; 23–26 °C, pH 4.0–7.0, 1–6 dGH; insectivore, floating foods, fruit flies; very peaceful, timid, no active tankmates, similar-sized characins and small catfish; six minimum; cohabits with other Carnegiella); Maidenhead Aquatics (fishkeeper.co.uk), Pygmy hatchetfish (max 2 cm; 23–27 °C; pH 4.5–7.0; soft, acidic water essential for breeding; dim; mature, gentle water; tight cover slides, block gaps; 6+, 10+ better; small tetras, pencilfish, corydoras, dwarf cichlids, small Loricariidae; sensitive to nitrate and swings; not bred in home aquaria); Aquarium Co-Op, Care guide for hatchetfish (pygmy is the smallest hatchetfish sold; mostly wild-caught, quarantine and treat; tight lid; prefer floating food, underfeeding common); Aquarium Co-Op, Cherry shrimp tank mates (dwarf cichlids go after shrimp); Practical Fishkeeping, Can I safely add some shrimp? (almost any active fish treats hatchling shrimp as food); Practical Fishkeeping, What can I keep with shrimp? (build the colony first; many fish medications unsafe for invertebrates); The Shrimp Farm, Red rili shrimp tank set-up and care (cherry-type Neocaridina: 65–85 °F, pH 6.2–8.0, GH 4–8). The shared water zones, shrimp-risk reading and stocking suggestions are our own.