Hi and welcome to the forum
If it went white first thing in the morning or when you turned the lights on, that is stress caused by going from a dark tank to a light one quickly.
If you did a water change or moved stuff around the tank, or did something to disturb the fish, they can also fade.
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Kanaplex is an antibiotic (Kanamycin) and should only be used on known bacterial infections that have not responded to normal treatments. Improper use and mis-use of antibiotics has caused drug resistant bacteria that kill people, animals, birds, fish and reptiles.
The Kanaplex might have killed the filter bacteria so monitor the ammonia and nitrite for a couple of weeks to make sure the filter is ok. If you do get an ammonia or nitrite reading above 0ppm, do a 75% water change and gravel clean the substrate every day until the levels are 0ppm.
Make sure any new water is free of chlorine/ chloramine before it's added to the tank.
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If fish look unwell, try not to add chemicals unless you know what is wrong with them. Quite often a partial water change can help. Unfortunately more often than not, people add medications when they aren't needed, or they use the wrong medication for the ailment.
The following link is about what to do if your fish get sick. it's long and boring but worth a read when you have some spare time.
If your fish ever looks sick or unwell, then the following steps might help. Test the Water and Clean the Tank. Test the water quality for ammonia, nitrite, nitrate and pH and write the results down in numbers. Check it for general hardness (GH) and carbonate hardness (KH) too if you can, but...
www.fishforums.net
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Regarding the angelfish. Do you have a bigger tank to move them into later on when they have grown a bit?