Angelfish Tank Mates: What to Keep and What to Avoid

Angelfish eat fish small enough to fit in their mouths, including neon tetras, and their long fins attract fin-nippers. They need a tall tank and turn territorial when spawning.

Angelfish (Pterophyllum) do best with peaceful fish that are too large to swallow and that do not nip fins. Small tetras such as neon tetras are eaten as the angels grow, fin-nipping species such as tiger barbs and serpae tetras target their long fins, and a spawning pair will defend a territory against other fish.

Predation on small tetras

Wikipedia describes Pterophyllum as predators of small fish and macroinvertebrates, and notes that in a community tank any fish small enough to fit in an angelfish's mouth may be eaten. Seriously Fish says Pterophyllum scalare may eat small fish such as tetras. Tropical Fish Hobbyist (TFH) calls the species largely carnivorous, says few livebearer fry survive in a tank with angelfish, and singles out the very common angelfish and neon tetra combination as particularly dangerous. The Seriously Fish profile of the altum angel (Pterophyllum altum) gives the same rule in plain terms: anything that fits in its mouth, including neon tetras, guppies and pygmy rasboras, is potential prey.

Fin-nippers to avoid

Wikipedia notes that fin-nippers such as tiger barbs often target the long fins of angelfish. A Practical Fishkeeping (PFK) feature on fin-nipping lists angelfish, Siamese fighting fish and male guppies as the most likely victims, and names the following species as known nippers:

Tiger barb (Puntigrus tetrazona), described as the most notorious nipper.
Serpae tetra (Hyphessobrycon eques), described as the best-known fin-nipping tetra.
Skunk loach (Yasuhikotakia morleti), which ranks highest among loaches for nipping.
Bumblebee and peacock gobies.
Several tetras and related characins: blue emperor, blue, white spot and Buenos Aires tetras, blind cave fish, black widow tetras and Congo tetras, and neon tetras when stressed or crowded.

PFK's prevention advice is to give fish ample space, use a tank large enough for top, middle and bottom swimmers to stay apart, and feed a varied diet little and often. In a separate answer on stocking angels, PFK says whiptail catfish (Rineloricaria) occupy a different niche and are largely ignored by angelfish, although the very long tail rays of some Rineloricaria species might be pecked.

Temperature and tank height

Adult P. scalare reach about 15 cm in body length and 20 cm or more in height, according to Seriously Fish, which recommends a tank of at least 100 × 40 × 50 cm, with at least 50 cm of height for adults. TFH observes that in small tanks many mature angelfish cannot fully extend their fins. Seriously Fish and TFH both give 24–30 °C for P. scalare, Seriously Fish gives pH 6.0–7.4, and TFH notes the species tolerates soft to hard water. Tank mates therefore need to be tropical fish that are comfortable in this range.

The altum angel is more demanding. Seriously Fish gives 28–32 °C, pH 4.8–6.2 and 0–5 °dGH, and says very soft water is mandatory, which narrows the list of companions much further than for P. scalare.

Pairing and spawning aggression

All Pterophyllum species form monogamous pairs, according to Wikipedia, and partners protect each other from threats. Seriously Fish and TFH describe pairs forming within a group and spawning on a vertical surface; Seriously Fish suggests starting with about six juveniles so that pairs can form naturally. Pairs leave the group to spawn and defend a temporary territory, chasing other fish away from the spawning site. Seriously Fish adds that males become more aggressive and territorial in spawning condition, and that angelfish may squabble with their own kind. PFK likewise reports that males grow more aggressive at sexual maturity and that occasional individuals are bullies. For adding several angels, PFK advises introducing six or more at once rather than singly or in pairs, and notes that juveniles get along better than adults.

Captive-bred lines have largely lost their brood-care instincts, according to Wikipedia, so parents often eat their eggs or young. General principles for managing territorial fish are covered in the managing-aggression-guide.