Cardinal Tetra Size

Many fish profile sites (including this one) simply state that cardinals can grow to be "up to 2 inches" (or 5 cm). However, Seriously Fish gives a length of 20-35mm, and FishBase (which generally uses peer-reviewed sources) gives a maximum length of "2.5 cm SL male/unsexed." These sources use standard length (SL), which excludes the caudal fin, rather than total length (TL), so that might explain part of the discrepancy. But looking at pictures of cardinal tetras, their total length obviously isn't 30-50% caudal fin.

So, experienced cardinal keepers, how big do they really get?

 

Of my 9, which I've had for no more than 4 months at least 3 are comfortably longer than 2.5cm. Probably closer to 5/6 who are longer. Most of the fish have increased in size quite considerably since purchase.

 

I have 12 cardinal tetras, some I have had for 2 years, the rest, 18 months. The larger ones are close to 2 inches.. maybe inch and 3/4. I haven't measured them, just estimating. They were pretty small when I got them. they have grown slowly for me, but then again I don't overfeed and sometimes skip feedings. I also don't change water that often (at first once a week, now twice a month) , if I were feeding more and changing water more often they probably would grow faster and bigger.

Keep in mind that in the wild cardinal tetras die off after a year. In the home Aquarium they can live 3-5 years if well taken care of. They are going to grow larger at home than in the wild since they are alive longer and presumably being well fed. That may explain the difference in website's data.

I checked my cardinal tetras , they seem to be 1.5 inches, the longest are the size of my lemon tetras. Anyway wanted to clarify.. they aren't 2inches long as I thought they were by now.

 

As noted above, most are lucky to live much more than a year in the wild, but can live 5 times as long in an aquarium. Given a big enough tank, they can become giants of their species. I have seen schools of Cardinal Tetras that were at least 2 inches SL. They were raised as a group in a 240 gallon plywood tank. I've also seen 3 inch Zebra Danios raised in another plywood 240. These tanks were 8 ft. long, had lots of plants, and the fish were very well fed. Give the fish space, food, and time to grow, and they will exceed natural maximums regularly.

 

Thanks for the replies! I have read that neon and cardinal tetras are basically annuals in the wild, so it would make sense for sources based on wild fish to report smaller maximum sizes.