hello a few questions... to make sure is my tank suitable for the space and fish that are in my tank now? the tank size is 40 gal. fish in tank now are 5 guppies,2 nerite snails, 3 zebra danio, 4 corydoras (peppered), and a bristlenose pleco, will a red throated panchax or a clown killifish work? does a red throated panchax or a clown killifish need to be in groups? will eBay be save to order killifish? will live aquaria work to order killifish? plz answer as soon as possible! thank you!!