Why Fish Selection Is Critical for Shrimp Keepers
Adult cherry shrimp measure 2–3 cm; juvenile shrimp and newly hatched fry are under 5 mm. At these sizes, the vast majority of aquarium fish will eat shrimp opportunistically regardless of their reputation as "peaceful" community fish. A fish that ignores adult cherry shrimp may methodically hunt every juvenile the moment they appear. For shrimp colonies to grow and sustain themselves through breeding, the selection of tankmates must be based on the smallest, most vulnerable shrimp size — not the adults.
The safest approach is a shrimp-only tank with no fish at all. But many aquarists enjoy the visual depth that fish add to a planted tank and want both. The solution is to choose fish that are physically small enough that they cannot swallow adult shrimp, or fish that have evolved behavioral traits making them disinterested in shrimp as prey. Dense planting and moss walls also play a critical role — shrimp that have multiple hiding spots survive significantly better in mixed tanks than shrimp in sparsely planted aquariums.
In Cambodia's aquarium trade, the fish most commonly kept with shrimp are small rasboras, nano tetras, and Otocinclus catfish — all of which have excellent compatibility records. Conversely, bettas, gouramis, and cichlids — all of which are extremely popular in the Cambodian hobby — are incompatible with shrimp in almost all cases and should never be combined with a shrimp colony you care about.
- ✦A shrimp-only tank will always yield the best colony growth — add fish only if you accept that breeding success will be somewhat reduced
- ✦Dense Java moss and mosswalls are the single most effective way to protect juvenile shrimp in a mixed tank
- ✦Watch a new fish for at least 30 minutes after introduction — if it immediately hunts shrimp, remove it that day before it learns the behavior permanently
Best Shrimp-Safe Fish: Otocinclus and Small Corydoras
Otocinclus catfish (Otocinclus vittatus and related species) are widely regarded as the single most shrimp-safe fish available in the aquarium hobby. They are small (3–4 cm max), completely herbivorous, and have no physical capacity to harm adult shrimp. Their diet consists entirely of soft algae and biofilm, which overlaps productively with shrimp activity on plant surfaces. Otocinclus and shrimp are frequently observed grazing side by side on the same leaf without any conflict.
Small Corydoras species (Corydoras pygmaeus, Corydoras habrosus, Corydoras hastatus — the nano corys) are excellent companions for cherry shrimp. They are bottom-dwelling scavengers that help clean leftover food before it decays, reducing ammonia risk. Their small adult size (2–3.5 cm) means they cannot swallow even juvenile shrimp, and their peaceful temperament means they do not chase or harass shrimp in any way. Standard-size Corydoras (C. sterbai, C. paleatus at 5–6 cm) are generally still safe for adult shrimp but may occasionally eat very small juveniles.
Both Otocinclus and nano Corydoras benefit from being kept in groups — Otocinclus should have at least 5–6 individuals, nano corys at least 6–8. Lone specimens of these social species become stressed and may develop unusual behaviors. In Cambodia, Otocinclus are available through planted tank importers; nano Corydoras species are less commonly stocked but can be ordered through Bangkok import channels.
- ✦Keep Otocinclus in groups of 5 or more — lone Otocinclus become stressed and may not survive long in a tank without social companions
- ✦Feed Otocinclus and Corydoras specifically with sinking algae wafers and blanched vegetables — do not assume they will survive on tank algae alone
- ✦Nano Corydoras (pygmaeus/habrosus) are the safest Corydoras for shrimp; avoid larger species like C. sterbai with crystal shrimp fry
Nano Tetras and Rasboras — Small Fish With Great Compatibility
Chili Rasboras (Boraras brigittae) are one of the most reliably shrimp-safe fish available. At only 2 cm maximum adult size, they are physically incapable of eating adult cherry shrimp and show essentially no interest in shrimp at all. Their vivid red coloration contrasts beautifully with the natural green-and-brown palette of a planted shrimp tank. They are shy fish that do best in groups of 8–12 and require stable water parameters with some acidity — conditions that overlap well with cherry shrimp requirements.
Ember Tetras (Hyphessobrycon amandae) are another excellent choice at 2 cm adult size. They are less timid than Chili Rasboras and add lively mid-water activity to a shrimp tank. Like Chili Rasboras, their small mouths make adult cherry shrimp safe, though very small fry (first week of life) may occasionally be picked at. In a heavily planted tank with moss, fry survival in the presence of Ember Tetras is still reasonably good. Green Neon Tetras (Paracheirodon simulans) and Celestial Pearl Danios (Danio margaritatus) round out the list of nano-sized fish with documented good shrimp compatibility.
Slightly larger community fish like Harlequin Rasboras (3.5–4 cm) and Rummy Nose Tetras (4–5 cm) present mixed results. They are generally not interested in adult cherry shrimp but will hunt juveniles consistently. If your primary goal is maximizing colony breeding output, stick to fish under 3 cm. If the colony is already established and large (50+ adult shrimp), slightly larger companions cause acceptable losses while adding visual interest.
- ✦Chili Rasboras (2 cm) are the gold standard for shrimp compatibility — they are physically too small to eat adult cherry shrimp under any circumstances
- ✦Ember Tetras work well in planted shrimp tanks but add very dense moss if you want good fry survival alongside them
- ✦Purchase nano fish and shrimp simultaneously from day one rather than adding fish to an established shrimp colony — territorial behavior is less likely
Fish to Absolutely Avoid With Shrimp
Betta fish are arguably the most common cause of shrimp colony loss in Southeast Asia. Despite their popularity and the marketing of "betta communities," bettas are predatory fish that will eat shrimp. Some individual bettas appear to ignore shrimp for months, then decimate a colony overnight. Others begin hunting immediately. The behavior is individual and unpredictable, meaning there is no "safe" way to keep bettas with a shrimp colony you care about. Even a supposedly peaceful betta will hunt juveniles consistently if not adults.
Gouramis present the same problem at a larger scale. Dwarf Gouramis (Trichogaster lalius), Three Spot Gouramis, and particularly Blue Gouramis are all efficient shrimp predators. Their long ventral fins are highly touch-sensitive and they use them to detect and locate prey — shrimp often trigger this sensory system and become targets. Pearl Gouramis are somewhat less aggressive but still present significant risk. Any Gourami larger than 4 cm should be considered incompatible with a shrimp colony.
Cichlids of any kind are incompatible with shrimp. Even the smallest cichlid species (Apistogramma, German Blue Ram) are ambush predators that will systematically hunt shrimp. In Cambodia where Flowerhorn, Oscar, and various cichlid species are extremely popular, it is worth emphasizing clearly: never combine cichlids with ornamental shrimp. Even Angelfish, often mischaracterized as gentle, will eat adult cherry shrimp efficiently once they discover them.
- ✦Never keep bettas with ornamental shrimp — no exceptions, regardless of the individual betta's behavior history
- ✦Any cichlid species, including Apistogramma and Ram cichlids, will eat shrimp — they are ambush predators by nature
- ✦If you have both bettas and shrimp and want to keep both, maintain completely separate tanks — there is no safe way to combine them
Using Moss and Plants to Protect Shrimp in Mixed Tanks
In any mixed tank where shrimp and fish coexist, dense vegetation is the most important survival tool for the shrimp. Java moss, Christmas moss, flame moss, and willow moss all create complex three-dimensional structure that shrimp navigate easily but larger fish cannot fully penetrate. Juvenile shrimp spend their entire early life within moss colonies, emerging only briefly to feed before retreating. Without sufficient moss, juvenile survival in mixed tanks drops dramatically.
Moss walls are a beautiful and functional protection strategy. Attach moss to a mesh panel (stainless steel mesh or plastic craft mesh) using fishing line or cotton thread. Within two to three months, a dense living wall forms that functions as both decoration and shrimp nursery. Place moss walls along one or two sides of the tank where shrimp can retreat easily. The visual effect in a planted tank is stunning — a living wall of green with shrimp visible grazing all over its surface.
Low-growing plants like Microsorum pteropus (Java Fern), Cryptocoryne, and Bucephalandra also provide shelter zones near the substrate where shrimp prefer to congregate. Building layered plant density — tall background plants, mid-level stem plants, low foreground, and moss surfaces — creates a habitat where shrimp can always find refuge within a few seconds. This multi-layer approach reduces fish predation on shrimp to a level where a colony can maintain itself even in moderately stocked community tanks.
- ✦A moss wall covering 30–40% of one tank side dramatically increases juvenile shrimp survival in mixed tanks — build one before adding fish
- ✦Attach Java moss to small stones or driftwood pieces and place multiple clusters at different heights for multi-level shrimp refuge zones
- ✦The denser the planted coverage, the more fish you can co-keep with shrimp — aim for at least 50% plant coverage of the substrate