Congo tetras with shrimp
The Congo tetra is one of the African tetras (family Alestidae), a large, peaceful schooling fish whose males color up spectacularly as they mature and grow a greatly extended dorsal fin and long filaments in the tail (Seriously Fish, Maidenhead Aquatics). It is Phenacogrammus interruptus, native to parts of the River Congo drainage in the Democratic Republic of the Congo (Seriously Fish); Tropical Fish Hobbyist Magazine gives Stanley Pool on the lower Congo as its type locality and notes the older name Micralestes interruptus. Most Congos in the trade are bred commercially in the Far East and Eastern Europe (Seriously Fish).
Congo tetra at a glance
| Congo tetra (Phenacogrammus interruptus) | |
|---|---|
| Adult size | 80 mm (3.1 in) standard length (Seriously Fish); 9 cm (3.5 in) total length (Tropical Fish Hobbyist); 12 cm (4.7 in) (Maidenhead Aquatics) |
| Temperature | 73–82 °F (23–28 °C) (Seriously Fish); 23–26 °C (Maidenhead Aquatics) |
| pH | 6.0–7.5 (Seriously Fish); 6.0–8.0 (Maidenhead Aquatics) |
| Hardness | 3–18 dGH (Seriously Fish); 5–20 dH (Maidenhead Aquatics) |
| Tank | 48 × 12 × 12 in (120 × 30 × 30 cm), about 29 US gallons, for adults (Seriously Fish); at least 4 ft long (Maidenhead Aquatics) |
| Group | At least 6, preferably more (Maidenhead Aquatics); a mixed-sex shoal (Seriously Fish) |
| Diet in the wild | Omnivore: small worms, insects, crustaceans, algae and zooplankton (Seriously Fish) |
| Temperament | Peaceful but timid and easily frightened; may scare shy fish with its active swimming (Seriously Fish, Maidenhead Aquatics) |
Will Congo tetras eat shrimp?
- Adult shrimp: at risk. None of our sources tested Congos with shrimp, but Aquarium Co-Op says to avoid medium to large fish with cherry shrimp, Practical Fishkeeping's Nathan Hill personally counts the larger tetras among fish that will eventually eat shrimp, and Maidenhead Aquatics says Congos shouldn't be kept with any tiny fish. In our reading a 3 to 4.7-inch fish can swallow a small male or a freshly molted cherry.
- Shrimplets: expect them to be eaten. Neale Monks at Practical Fishkeeping says pretty much any active fish, even one as small as a tetra, views hatchling shrimp as food, and Seriously Fish lists crustaceans in the Congo's wild diet.
- Eggs and berried females: eggs are safe while carried under the tail, but a stressed female may drop them (our reading).
Even Amano shrimp, the usual fallback with bigger fish, are not a sure thing next to an adult Congo in our reading, so keep a cherry colony in its own tank and treat any shrimp in a Congo tank as a bonus. For gentler choices, compare ember tetras with shrimp, emperor tetras with shrimp and rummy-nose tetras with shrimp, or see the full cherry shrimp tank mates list.
Matching the water
Seriously Fish suggests water on the soft, acidic side of neutral with good circulation, within 73–82 °F, pH 6.0–7.5 and 3–18 dGH; Maidenhead Aquatics says Congos acclimatize to a wide range, from pH 6.0 to 8.0 and 5–20 dH, at 23–26 °C. Cherry-type shrimp tolerate 65–85 °F, pH 6.2–8.0 and GH 4–8 (The Shrimp Farm). By our comparison, about 74–78 °F, pH 6.5–7.5 and GH 5–8 suits both. Caridina such as crystal reds prefer cooler, softer water (see crystal red shrimp care), and with this much risk we wouldn't pair them (our reading). See shrimp tank pH, GH and KH explained and shrimp water parameters.
Tank size and setup
- Size: Seriously Fish suggests 48 × 12 × 12 in, about 29 US gallons, for adults, and Maidenhead Aquatics says at least 4 feet long. Young fish can start in smaller tanks (Seriously Fish), but they grow.
- Swimming space and dense cover: Seriously Fish suggests driftwood branches, floating plants and anubias, with plenty of open swimming space; Maidenhead Aquatics adds areas of dense planting so the fish feel secure. Thick moss and plant mats give shrimp somewhere to hide (Aquarium Co-Op). See java moss for shrimp and best plants for shrimp tanks.
- Clean, well-oxygenated water: Seriously Fish says Congos are sensitive to water quality, and the males' fins may not develop and the fish lose color if standards slip; Maidenhead Aquatics wants clean, well-oxygenated water with good flow. See shrimp tank water changes.
- Shrimp-safe intake: with stronger flow, cover the filter intake with a sponge so shrimplets aren't pulled in (our suggestion). See shrimp-safe filters.
Group size and behavior
Maidenhead Aquatics calls Congos active but fairly timid and easily frightened, and says it is very important to keep them in groups of at least 6, preferably more. Seriously Fish recommends a mixed-sex shoal, and a Practical Fishkeeping African biotope build used an even split of males and females to minimize aggression. Males are larger and much more colorful, with the long dorsal fin and tail filaments (Seriously Fish, Maidenhead Aquatics).
Other tankmates
Seriously Fish suggests other tetras, rainbowfish, Corydoras, Loricariids, Synodontis and peaceful cichlids such as Pelvicachromis, and warns against fin-nipping or boisterous fish, which would shred the males' fins. Maidenhead Aquatics agrees: no boisterous, fin-nipping fish and no tiny species. Cichlids hunt shrimp (Aquarium Co-Op), so if shrimp share the tank, stick to peaceful catfish. See corydoras with shrimp, bristlenose plecos with shrimp and serpae tetras with shrimp (a fin-nipper to keep away from Congos).
Feeding both
Seriously Fish says Congos are relatively unfussy, but live and frozen food should make up a good share of the diet for best color. Maidenhead Aquatics suggests flakes, algae-based flakes, slow-sinking pellets and frozen mosquito larvae, brine shrimp and Mysis. Feed the Congos first, then drop sinking shrimp food into dense cover (our suggestion). See best shrimp food.
How to add Congo tetras to a shrimp tank
- Shrimp first. Practical Fishkeeping suggests letting the shrimp colony build up before adding fish; hiding places and well-fed fish reduce losses.
- Remember they grow. Seriously Fish says Congos are usually sold as 1.5-inch juveniles, so a group that seems harmless at first will be twice that size later (our reading).
- Acclimate slowly to your water. See how to drip acclimate.
- Watch shrimp numbers for the first few weeks, especially after molts.
- 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
- Buying small juveniles for a nano tank; adults need about 4 feet of swimming room.
- Keeping two or three, which leaves a timid fish nervous and pale.
- Adding fin-nippers such as serpae tetras that ruin the males' fins.
- Expecting a cherry colony to keep breeding next to a school of 3-inch-plus fish.
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 Congo tetras eat cherry shrimp?
They will eat shrimplets, and in our reading small or freshly molted adults are at risk too. Congos grow to 3 inches or more and eat small crustaceans in the wild (Seriously Fish). We rate them a high risk.
How big do Congo tetras get?
About 3.1 inches (80 mm standard length) per Seriously Fish, and up to 4.7 inches (12 cm) per Maidenhead Aquatics.
What size tank do Congo tetras need?
About 48 by 12 by 12 inches, roughly 29 US gallons, for adults (Seriously Fish); Maidenhead Aquatics says at least 4 feet long.
How many Congo tetras should I keep?
At least six, preferably more, in a mixed-sex group (Maidenhead Aquatics, Seriously Fish).
Are Congo tetras aggressive?
No. They are peaceful but timid, and their active swimming can unsettle shy fish (Seriously Fish). Keep them away from fin-nippers.
Are Congo tetras good for a nano tank?
No. They are usually sold at about 1.5 inches but grow much larger and need a tank around 4 feet long (Seriously Fish, Maidenhead Aquatics).
Sources: Seriously Fish, Phenacogrammus interruptus (Congo tetra) (River Congo drainage, DR Congo; most trade fish bred in the Far East and Eastern Europe; sold as drab gray juveniles; 80 mm SL; 120 × 30 × 30 cm, about 29 US gal, for adults; driftwood, floating plants, anubias, swimming space; soft, acidic side of neutral, good circulation; 23–28 °C, pH 6.0–7.5, 3–18 dGH; omnivore on small worms, insects, crustaceans, algae, zooplankton; live and frozen foods for color; peaceful but may scare shy fish; tankmates; no fin-nippers or boisterous fish; mixed-sex shoal; males larger with extended fins; sensitive to water quality, easily frightened); Maidenhead Aquatics (fishkeeper.co.uk), Congo tetra (12 cm; 23–26 °C; pH 6.0–8.0, dH 5–20; community with no long-finned fish; timid; groups of at least 6; tank at least 4 ft with dense planting; clean, well-oxygenated water with good flow; no boisterous, fin-nipping or tiny fish; flakes, algae flakes, slow-sinking pellets, frozen foods); Tropical Fish Hobbyist Magazine, Phenacogrammus interruptus (Stanley Pool type locality; formerly Micralestes interruptus; 9 cm TL; adaptable water chemistry); Practical Fishkeeping, How to set up an African biotope aquarium (even split of males and females to minimize aggression); Aquarium Co-Op, Cherry shrimp tank mates (avoid medium to large fish; cichlids hunt shrimp; dense foliage hides babies); Practical Fishkeeping, can I safely add some shrimp? (any active fish, even a small tetra, sees hatchling shrimp as food); Practical Fishkeeping, What can I keep with shrimp? (larger tetras and barbs likely to eat shrimp in the author's view; build the colony first; hiding places and well-fed fish reduce losses; 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 zone, the high shrimp-risk rating and the stocking suggestions are our own.