Originally Posted by DKRST
I purchased 5 angelfish and noticed that each of them will occasionally "shimmy". It almost looks like they are vibrating in place for a second or two, then they go about their business. Is this a normal behavior or a reaction to external parasites? They came with ick, complementary, from the LFS.
If fishes were purchased from fish store as opposed to local breeder, then the chance of parasites such as Ich,fish lice,gill flukes,is more probable than not, considering the volume of fishes that pass through the store tanks, and numbers of fishes kept in same.(especially ,Petco,pet smart,walmart.)
I do not believe based on my own expieriences with species mentioned, that the described behaivor is normal. Have seen larger Angelfish perform what you describe during mating but usually this type of behaivor was confined to a pair,not all fish.
Angelfish prefer warm,78 to 82 degree F not too hard water with no ammonia or nitrites as you no doubt are aware.
If treating for ICH or other parasites, and depending on meds used,,,it is wise to monitor the water due to effects of some medications on biological filter. If biological filter is compromised, this could lead to ammonia or nitrite level's increasing to dangerous level and described shimmying could be result of considerable discomfort.