Pufferfish spawn in drained out ocean base

I just recently drained out a section in the Warm Ocean biome, and on some occasions I noticed droppings of pufferfish in my base. I even saw a group of pufferfish spawning in my base. The spawns occurred on the edges of the base, and it is annoying to see the droppings intermittently. I have attached a picture of one of the situations of the pufferfish dying in my base.