Baby tilapia? Or baby algae eater?

[Hydroponics Curacao]

Hi guys!

A few days ago I found some baby guppies in my fish pond. And I caught them and put them in a mini aquarium in my room. 

Today I went to feed the fishes in the pond and I found a lot of babies. I collected them thinking they are guppies. But when I put them in the mini aquarium, I realized that there's a big difference between the ones I caught a few days ago and the ones from today. My conclusion is, that they aren't guppies. 

Now my Question is, What are they???

• I saw that the swim on the water surface but when you try to catch them, they dive deeper into the water. Baby guppies don't do that. They stay on the surface.
• They swim very fast. Baby guppies don't 
• The ones I caught today are all black/grey. Guppies have different colors even when they are just born. 
• Their structure is other compared to the guppies. 
• They are slightly bigger than the guppies. 

Photos:

The one swimming alone in the upper left corner is a guppy.

[Debra Colvin]

Too soon for me to tell. I've had guppies. Maybe they're wild type goldfish or carp? The behavior fits for goldfish...

[Hydroponics Curacao]

No. It can't be goldfish. Because in that pond I have tilapia, guppies and algae eater. And guppy it isn't. So it has to be either tilapia or algae eater

[Andrew]

Tilapia. They look just like mine. I only have tilapia.

[Hydroponics Curacao]

Great! But they have been eaten by the adults..

Andrew said:

Tilapia. They look just like mine. I only have tilapia.

[Chris Smith]

Those look like tilapia fry. What species of fish are in your pond that could be breeding???

[Hydroponics Curacao]

Tilapia and algae eater