Zebra danio fry: how long to grow?

[JohnPaul]

I am asking this question hoping beyond hope that the answer provided by someone will help to relieve my fears that I have completely lost it.

About a month ago I added my first batch of fish to my tank: 8 zebra danios and 3 cory cats. Talking about that was my first-ever post here on AA, in fact.

That first night, one of the zebras died. I fished him out of the tank the next morning. About a week later, one of them died. Again, fish was removed from the tank.

Now, last time I checked, 8-2=6. Someone please correct me if I'm wrong.

So over the 3 weeks or so, I have been observing my tank lots. I mean, LOTS, because I had been dealing with some sick dwarf neon rainbowfish. Also a good friend who lives across the hall is in here all the time, so he watches as well. Both of us agree that there were definitely 6 zebra danios.

Well, about 3 or 4 days ago, he says to me, "John Paul, how many zebras are there? I swear I can count seven." After making fun of his math skills, I look at the water...sure enough, there are 7. Absolutely, positively 7.

Now here's the kicker--one of them is less than half the size of all the others. They were all roughly the same size when I got them at the lfs (maybe 3/4" or so). Most of mine are now twice that size...roughly 1.5." Except for one, who is no more than 3/4", probably closer to 1/2."

Is there any chance this guy was hatched in my tank? Could an egg hatch and grow to more than 1/2" in a month? (And do so without me ever seeing him swimming around the tank?)

Or am I going completely crazy...

 

[BrianNY]

The answer is yes JohnPaul. I just encountered the same thing with some pristella tetras. Although I didn't count them, while doing a wc I noticed 2 smaller ones about a third the size of my others. In another month they were all about the same size.

 

[JohnPaul]

cool, thanks. Looks like I'm a dad! (Or...er...a grandpa. Or something.)

 

[Frank_the_Tank]

I got 3 zebra danios to cycle the tank with, and one of them was small, and hung around at the top for a couple hours not really moving and then died. About 3 weeks later I went and got another 3, because the first batch was all males, and Petsmart had a batch of females so I got 3 to give them a little variety with the color differences. One of them was very, very small, and I was worried that it would fair about as well as the other runt of the first "litter". Well a couple weeks later and today I was looking at the tank, and I could barely pick out which fish was the smaller one, it's grown like a weed.