Cleanup crew for temperate tank?

[seaponies]

I have a 65g tank with a 20g fuge.

This is a temperate tank kept at 65f for abdominalis seahorses.

I'm doing fine with algae eating snails (margarita, red foot moon) but I need something to clean up the sand bed and eat leftover frozen mysis.

I'm not sure what might fare well in these temperatures.

Any suggestions?

Thanks

Dana