DEAR LORD CHILD!
what a mess
i'm assuming this is your first tank?
welcome to the forum and the ever so addicting world of fish keeping
for newer fish keepers a good rule of thumb is one inch of fish per gallon
you use this rule by calculating the adult size of the fish (there are some fish that produce less waste and are cleaners, so they are acceptions to this rule)
you currently have 62" of fish in your 15gallon
thats ALOT of extra fish!
you should only have 15", or 20" tops since you have small schooling fish (the can be a bit more crowded)
my advice to you is to get another tank
try to get a bigger second hand tank rather then another small, new tank
something VERY important about the true flying fox (not the imposters) is that they are the sharks of catfish
i know this sounds odd but they have the same temperment as a red tailed black shark (a very territorial shark who does not live peacefully with anything that even resembles its own species)
firstly he will get to be 6" and is very active if healthy, so 15gallons (especially so crowded) is NOT enough room
secondly, he may be a peaceful little baby but as soon as they get to be about 3" they start to attack anyone in their "territory", especially around feeding time
and if fed any type of meat (blood worms, shrimp, etc) they usually get quite aggressive
he needs LOTS of caves and plants and if in a small enough tank will claim them all
people often mistake him for siemese algae eaters, chinease algae eaters, or other false flying foxes
the bigger the tank
the more peaceful these fish will be
the smaller and more crowded the tank
the more mayham will break out
some people think that due to their sucker type mouths that they cannot do harm to the other fish
this is wrong
although they rarely leave marks,
they will chase a fish constantly and bump it until it becomes stressed and disease ridded
sorry to be so negative but simple water changes will not do
its better that someone tell you the facts now, rather than have you find out later when your fish start to die
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