Malachite green

[i have crabs]

using hypo in a tank with inverts is not possible and it will kill any live rock you have in thier, i used the hypo treatment for the first case of ich i ever got and it got rid of the ich but caused a big bacterial infection wich killed more fish than the ich the nitrates flew through the roof when the rock died so 2 buckets of salt later and a refractometer i desided next time it would be copper,wich i now have a 67g qt that i use copper in before any fish go in with any others