Flagellates: Protozoans such as these cause persistent trouble in situations where angelfish are stressed. Hexamita is one that is very prevalent. It is thought to be present in all angelfish, at least in small numbers, and an outbreak is what you're trying to prevent. It appears to explode in numbers if the fish are too crowded, overfed or being overly stressed by some other situation in the aquarium. Stressing your angelfish, is what you need to avoid. Symptoms: If the angelfish is still eating, they will pass a white, chalky feces. Appetite will decrease. No external symptoms will appear on the angelfish. They are prone to secondary infections of bacteria and other parasites when in this weakened condition. To cure, relieve stress and then raise the tank temperature to 95° F for 7-10 days and medicate with metronidazole, or a medicated food that contains it.
Introduction to angelfish tank - YouTube
Another point is that very few people want to or have the time to breed angelfish. Most angels will cannabilize their eggs so removing them and transferring to another tank is advisable. Hatching and raising tiny fry can become very problematic and time consuming for the average person. The profits realized from the brood usually do not justify the time, energy and effort that have been invested. Most fish keepers just want an attractive addition to their tanks and buying an angel and keeping it at 7.6-7.8 is not really a big deal!
My other 29 gallon angelfish tank. - YouTube
The justification that the fish will not attain adult size in captivity, and therefore not require such a large tank is erroneous and indicative of poor husbandry philosophy. The health of the fish kept under such methodology will suffer sooner or later. There are fish that do not suffer as greatly from such an approach (within reason) such as the triggerfish, or many grouper species. While a genus or species being generally forgiving in this regard should not be interpreted as license to cramp them into tight quarters, the Pomacanthids offer no such level of forgiveness. They eventually and invariably show faded color, and/or withering health, and begin a long, (or not so long) downward spiral. If that all sounds discouraging, no worries, the good news is that you can split the difference between a small inland sea in your living room, and a tank that is too small to allow for a long and healthy life for your angelfish. The bottom line here is that you will have greater success the more room you provide from the get-go, even beyond the sizes I'm about to list. This means that despite it's small size, a 3" juvenile Queen angel will do much better in the long run starting out in a 180 gallon tank than it will an 80 gallon tank, even though from a space perspective, 80 gallons would seem large enough for the time being, and certainly would be for a 3" Hawkfish. Remember, we're concerned just as much about the psychological effect of the environment at this point, and by extension we are managing the stress level, immune response, growth rate and color of our specimen. When upgrading to something larger, do so before he's starting to look too small for the 180 gallon, say around 6" or so. To reiterate, artificially stunting these fish by keeping them in inadequate quarters is not appropriate husbandry practice, despite how common this practice is, whether it be from ignorance, or lack of space, or limited finances. While the above statement moves a majority of aquarists out of the realm of being able to keep these fish, considering the frequency with which these fish die under the care of well meaning but ill-equipped hobbyists - I think this is justified. This family is without a doubt for advanced keepers in multiple respects. Just because a fish is collected and imported, does not mean it's appropriate for your living room. The aquarist must be, above all things, conscious of the well being of the animals he/she keeps.
My other 29 gallon angelfish tank