I have a few questions about columbian tetras (Hyphessobrycon colombianus I believe). I have 8 adults in a 35 gal tank. In January, 17 fry appeared. They are now an inch long and look like mini versions of the adults. They've looked like this for a few weeks. I'm curious how long it takes for them to reach the same adult size. I'm also wondering if the tank they're all in (35 gal) can biologically handle it, or if I should move some into my other 35 gal. There's 25 in total, young and adults.

In terms of adult aggression towards fry, the point is moot here lol. They all swim and dance together. When the fry were smaller, the adults would form a circle around them at night time, like elephants do with their young. I wonder sometimes if this pointer exists because there usually isn't enough tank space. There's never been any aggression and not one fry has parished...if anything, I fear MORE appearing LOL!

I would move them...maybe consider splitting the group in half . Crowding young, growing fish fry together actually slows down (or even halts) the growth for most of the fish.

As for how long they take to grow, I'm not sure. It depends so much on water quality, size of the tank, genetics, diet, etc.

Ok, thanks! So a group of 12 and 13 are ok? I thought that would make the groups a tad small. I was thinking more like 15 and 10, but I can do half and half!

10 and 15 is fine, I just meant to split the group, it doesn't have to be exact .

lol noted! Thanks