i have noticed today and yesterday my fish wont stop opening and closing their mouths. i just did a massive water change as well tested everything and nothing was a problem but its still happening. i did however have to lower then ph and the water felt warmer then usual. the fish at concern are a dwarf gourami and a angelffish along with 2 albino cory catfish and 6 neon tetras all in a 29 gallon tank. i have a ligjt on the whole day as well has plastic plants and drift wood. The fish were fine but recently the gourami has been chasing yhe angel fish off and on. it seemed to help that i changed the tank around but im still worried sbout the rapid opening and closing of the mouths any help?