Animal Spawning from the animals included in this mod is different from vanilla animals

[Tacit-Knowledge]

I play on a multiplayer server with my father, and we tried to keep a turtle inside our base and in the frog pond we were able to enclose pet frogs in. But what keeps happening is that the turtle was able to get out. However, another weird thing is even though it is completely enclosed, both turtles and catfish will randomly spawn in and out of it daily. I think the issue is that the vanilla mobs were coded to be able to recognized that they are enclosed in something by the player, so they stay there. But the ones in this mod do not have that behavioral coding yet. Is there a way to fix this on the server?