How big do they get?

which species? If you're referring to Polypterus bichir bichir then I don't know, but I can tell you this species is near impossible to get due to its rarity. However, if you're talking about the common "bichirs" also sold as dragon eels, well these are Polypterus senegalus and will max out around 12" or smaller. :)

If it's a different species you need info on just say so and we'll try to help you out. :)

thats what it is thanks for the info.