I'm setting up my first aquarium, getting the cycle started right now on a 20 Long. My sole intention from the beginning has been to use it for a blue crayfish, with only a few danios or tetras due to the reputation crayfish have for not getting along with tank mates (I'm fine with the cray eating less expensive fish like that, but I don't want anything harming the cray). A friend of mine had a tank set up for a goldfish and also had a suckerfish (pleco?) - her goldfish died and she wants to dismantle the aquarium, but needs to get rid of the suckerfish first and asked if I would take it since I'm starting a new aquarium. I just want to make sure that there will be no problems between the two, at least none that would harm the crayfish. I'm looking at getting one of the electric blue crays for the tank, if species matters at all.