Angelfish are good with the generic "tropical fish" water conditions. Stable pH, about 78 degrees, no ammonia, no nitrites, low nitrates.
Freshwater angelfish, Pterophyllum scalare, are medium-sized from the tropical forests of the upper Amazon region in South America. They live in weedy, brushy backwaters with little flow or current. Although most fish in the hobby are captive-bred and have been acclimated to a wide variety of water conditions, the wild species come from soft acid water. It is my opinion that captive-bred fish do better under these conditions as well.
Most saltwater angelfish are hardy in the home aquarium but it can be difficult to acclimate them to life in captivity if they were wild-caught. It is also important to note that adult angelfish can be very destructive to reef habitats so you may want to limit decorations to live rock rather than corals and other delicate invertebrates. As for the water conditions angelfish prefer, a slightly alkaline pH range between 8.1 and 8.4 is ideal with moderate hardness between 8 and 12 dKH.
How to Care for an Angelfish: 11 Steps (with Pictures) - wikiHow
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3) Water conditions - Angelfish are GENERAL more tolerant of excess nutrients and metabolic wastes (such as nitrate), but not by a lot. Despite the fact that many have kept angelfish in deplorable conditions (no water changes), these fish are not really happy. Discus require clean water (water changes) ... and angelfish THRIVE in clean water. CONCLUSIONS - ANGELFISH DO REAL WELL UNDER DISCUS CONDITIONSAngelfish are endemic to the Amazon basin. In nature, they are found in soft, acid water that is very warm most of the year, usually around 80° F. Don't worry if you can't match these conditions in your aquariums. The domestic angelfish, most of which are many generations removed from wild stock, are a very adaptable animal. We have experienced little or no problem raising angelfish in water between 4.7 and 8.7 pH, and from very soft all the way up to very hard water. If your water doesn't naturally fall into this range and is extremely hard or alkaline, the use of a de-ionization filter or reverse osmosis (R.O.) filter can bring it into an acceptable range for you. R.O. filters are usually hooked into your main water supply and produce the equivalent of distilled water from the tap. The cost of a unit can range from less than a hundred dollars to over $5000, depending on the size and quality of the filter needed. Another means of altering pH is with easily obtained chemicals. This is one method that we prefer to stay away from, because with the chemical method, pH is prone to radical jumps if the water isn't properly buffered. Try to remember that it can be very time consuming to buffer the water, alter the pH, or adjust the hardness of your water supply. If it isn't stable after altering, the swings in pH are more stressful, than simply keeping the angelfish in less than ideal water. As we said before, most angelfish varieties will do well in a large range of water types, so avoid altering the water if you can.