hi bro,
i do have a harlequin shrimp , and it is a very nice shrimp. but for me, it hides most of the time unless i dont feed it a starfish.
not sure if its just me...
Your current set up is ok. But I think your tank is still cycling. Might be getting ammonia spikes that have been killing off yr fish. Small water changes and stop feeding for a couple of days. See whether yr nitrate drops.
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