Altum angelfish (Pterophyllum altum) show up less often in pet shops than their cousins the common freshwater angelfish (P. scarlae). While altums are arguably the more handsome fish, their demanding care requirements explain this discrepancy. Altum angelfish are extremely sensitive to water conditions and require more specialized foods than their more common cousins.
Since most captive altum angelfish are wild-caught, they require at least two weeks' quarantine before introduction to the home aquarium. During quarantine, set them up in an established tank with lots of plastic aquarium plants. Look for signs of disease or injury like fin rot. Of particular concern to keep an eye out for are black spots on the fish that look like pepper. These are the cysts of a protozoan parasite. If you see them, treat the disease with a commercially available remedy. This parasite, rarely fatal, can leave your fish looking ill. Do not add new fish to the main tank until they are healthy.
Altum angels are one of the few aquarium fish for whom a deeper aquarium is better than a longer one, since altums can be almost a foot tall. For their main display tank, you can keep up to three altums in a 55-gallon aquarium. During quarantine, you can use a 20-gallon tank for a single fish. In their display tank, plant the tank densely so the fish feel safe. Also, use a soft substrate like sand since they like to dig. Most important, make sure the aquarium is already cycled since ammonia is extremely toxic to altum angels.
Altums have very exacting water requirements for freshwater fish. However, if the conditions are met, altum angels generally thrive. They need water between 82 and 86 degrees Fahrenheit. The water must be soft and acidic, with pH between 4.8 and 6.2. Above all, the water must be exceedingly clean, since ammonia can kill them. Avoid copper-based medications, since these are toxic to altum angels.
Unlike common freshwater angelfish, altum angels will rarely eat flake food. Wild-caught specimens will usually eat only live food at first. Altum angelfish will generally eat live brine shrimp enthusiastically. You can wean some specimens onto frozen foods by feeding both live and frozen food at the same time. Bloodworms keep altums healthy but are generally available only frozen.
Paradoxically, altum angelfish are peaceful but predatory. They should not share an aquarium with anything small enough to fit into their mouth, including aquarium staples like guppies and neon tetras. Altums will not bother larger aquarium fish for the most part. Altum angelfish are about the same size as discus fish, who need similar care. You can also keep altums singly or in schools depending on how big your tank is.
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