Pokeshells and Sani Shells destroy their eco systems.

[stedam]

It is just a matter of time before Sani Shells destroy the ecosystem they spawn into. All the fish will die, given enough time. The same goes for the Pokeshells killing all the Snails. It breaks game immersion; this ecosystem was there and should remain there without duplicant involvement of removing the eggs. 

Options:

(1) remove crabs from the biome - not good.

(2) keep aggression but have crabs attempt to bury their eggs, and become aggressive only when this is not possible or when the egg is burried out - good

[NNOUS]

this could help by giving fishes a suitable living zone, like f.e. beacon like to stay at 2 tile form surface and 2 tile form bottom, which would help them stay out of deadly crab whiping at them

[stedam]

That's why I argue for Pip burying like mechanic for Shell variants. It would activate the aggression only if the duplicants came to dig the eggs out of the ground.

This pairs well with the theme that if Duplicants do not intervene, the ecosystem exists undisturbed.  

Additionally, the devs then do not need to adapt all the fish, just one critter.
P.S. Dear Dev, please add salt water towards Sunishell egg chances... in the image above, you see the Pokeshell egg, losing the Sanishell morph from the ecosystem in the next generation. It will not affect the other two biomes - starting biome has pokeshells on dry land and the cold ocean variant of the biome has brime.