Are you talking about the true dwarves? They can harm fish, but it's really rare. If they can find a sick, dying, or dead fish, they will definitely take advantage. Your cray will enjoy all of the hiding spots.
I'm using root tabs. I moved it recently. It was in the shadow of a regular sword and was not in the best shape. Now, it's starting to put out lots of new growth from within. I believe I will cut off the outer leaves that don't look healthy.
I work in a water resource lab. The next time I change the cuttlebone in my tank, I'm going to see what results I may get in some of our common tests concerning that outer gross and stink of an old cuttlebone.
I didn't realize Frogbit grew as fast as it does. This picture was taken today, two weeks since I thinned it out so that there was only 1/3 of the water covered. I'm glad it's sucks up Nitrates quickly.
Is the cray that you have a regular sized cray? If so, it would probably eat a dwarf cray. Also, the good thing about the dwarf crays is that they are not strictly nocturnal so you will see them out and about throughout the day.
It didn't make it through the afternoon.
It didn't make it through the afternoon. I pulled it before it started decomposing.
It was a young cray. It was about 1/2 inch when I got it and I've had it for about 6 months.