I found some of these in san antonio, also called von-rio tetras but when I looked them up I found they are officially named flame tetras. not real sure where the von rio came from other than where they are from maybe. I believe these will get larger than cardinals but would be much more hardy. I also suspect they will end up being a big nippy compared to cardinals being that their shape is common to the nippier type of tetras like serpae, blackskirt, lemon, etc which have reputations of being fin nippers from time to time so you might consider that with other tank mates when purchasing. kyle