I have a no-filter small tank where I keep my betta. There is a small pothos inside, as a way to absorb all the urea. But just today I realized he keeps on lounging towards the surface till his snout and eyes break the water surface. He does this repeatedly about 4-5 times, then stops and swims normally. I took him out and put him in a new dechlorinated water, just in case, with air bubbles.
Do you have any idea why he is doing this? Is it normal or a bad sign?
Bettas are anabantoids, commonly known as labyrinth fish after the labyrinth organ, which is a kind of lung-like extension of the gill tissue which can absorb oxygen from air.
For labyrinth fish, occasional surface gulping is quite normal and is a supplementary breathing action. This doesn't mean the fish isn't suffering from ammonia, nitrite or chlorine poisoning as you would generally assume from other fish families, but it is not a smoking gun in this case.
Still, it would be prudent to get a test kit for ammonia and nitrite, and consider installing a simple filter.
