With the objective of water purity, the frequency/volume of REQUIRED water changes is relative to the tank maintenance, stock level, feeding and filtration/purification. 50% weekly is just fine and probably 20-50% is good.
The very best maintenance is routine weekly water changes - it can make all the difference as the "solution to pollution is dilution".
As far as food, feed the live/frozen foods sparingly as they are great treats but unless you have a wide variation, they are not nutritionally sound. Also, read the labels on commercial fish foods. Many list fish meal and starches (wheat, oat, soy, rice flour or gluten) as main ingredients. Fish don't eat flour in nature! The best fish foods are made from whole fish....or at least fishmeal made from whole fish.
Omega One and New Life Spectrum meet this simple test.
Feed two or three times a day but only an amount they will consume in a couple of minutes. An objective is not only to not have uneaten food that will decay but also realizing that fish will consume much more food than they need (natures way as there are often lean times) and this is generally not healthy (just as us over eating is not healthy).
Originally Posted by Marbellohsdad
How often are you supposed to change the water in a 20 gallon tank for 1 juvenile angel ? I changed 50 to 60% of the water once a week is that too much?
Also how often do you feed them, I give mine 2 meals in the morning 1 at night.