sorry can't help you with your crayfish question, but stocking wise, I don't think you can go wrong with CA cichlids like viejas, cons, HRPs, JDs, Jags, etc... I say CA cichlids because you said the temperature fluctuates between winter and summer and even with that depth, the water temp will vary slightly and Central American fish are hardy when it comes to water params (IME). gl keep us updated!