Well...You have schooling fish who need schools of at least six in that tank. The x-ray tetras, neon tetras, and cardinal tetras, as well as the black neons and the black harlequins all should be in a school of at least six. Obviously you can't do that because then you'd have 30 fish in what amounts to around a 19 gallon tank. When tetras and other schooling fish aren't kept in proper schools, they can become aggressive and display unnatural behaviors, like nipping and fighting. I would recommend choosing one type of schooling fish, stocking up on them, and returning the rest. For example:
8 neons, maybe 4 or 5 guppies, and the betta. This should work out okay. Substitute any of the tetras or rasboras for the neons, if you'd like. Alternatively, if you got rid of the guppies as well, you could have maybe 2 schools of 6, of 2 different species.
It's a mistake many beginners make (I did it too) so don't feel bad, but at least now you know what to do
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current setup:
5.5 gallon low-light planted tank
-1 dwarf puffer named Beep.
for reference: my name is Julie
