I to wonder about the introduction of new fish
look for hairs hanging from your fish
i had some laps with a pericite that looked like hairs simular to gill fluks but were all over not just the gills
Are there any fish you shouldn't mix them with?
In my experince
plecos, cichlids id stay away from
i also had trouble with a skunk loach constantly harrassed them
Known to be escape artists, as for tankmate currenty i have mine in with endi, ornate(will not work long term) also eartheater, large barbs, Spotted Pike Characin, dehizi, seg