Is it bad luck to keep coins from a money tree that broke? i added it to my fish tank. Now 1 of my fish dead.?

I mean i still have 2 more that r still alive. Do you think it was the coins, they say "never keep broken things", i collected the coins n put them in the tank for further prosperity, i practice feng-shui. Or do you think the fish was simply sick? i just got them yesterday..? dude at the pets tore said my water temp was fine.. i don't get it!!! sum1 please help. I'm so sad =(