Category Archives: Paludarium

Why are they called “splashing tetras”? You’re about to find out in this post 🙂

Copella Arnoldi: Meet the splashing tetra!”

The splashing tetra is a fish that was sick of other fish eating their eggs. So they thought of a very smart thing to keep the other fish from eating their eggs: They lay their eggs ABOVE water, not in it!

Easier said than done… It requires them to jump out of the water, lay the eggs on surfaces above water, fertilize the eggs and then manage somehow to keep them wet until they hatch… And the splashing tetra did all of that.


How they lay their eggs

So how do they do all of this magic? As the female is getting thicker and thicker, it becomes clear she is producing eggs. The males start courting her, and at some point they form a couple.

The male now starts “test jumping” to several objects, mostly leaves growing above the water surface. They can jump up to 10cm:

Splashing tetra male jumping out of the water to test out places to have their babies hatch

After a spot has been determined, both male and female line up just under the water surface. By gently “buzzing” their bodies they communicate with each other and synchronize the jump they’re about to make:

Getting ready to jump… They must jump together and this requires a very exact timing.

Then they’re off! They both jump out of the water, and this picture clearly shows how well synchronized they are when they do:

Both male and female splashing tetras jumping synchronously out of the water to lay their eggs.

When they hit the surface where they’ll be laying their eggs, they will stick to that surface for a second. The female lays her eggs while the male will fertilize them:

Splashing tetra male and female sticking to a leave above water to lay and fertilize their eggs.

After they have laid some eggs, they’ll fall back into the water:

Male and female splashing tetras falling back into the water after laying egss on a leave above the surface.

They will now repeat this until they have laid between 50 and 100 eggs.


New babies about to be born!

Now this is where the splashing tetras get their names from. The eggs that were laid above water need to be kept wet. This is why the male splashing tetra will stay with the eggs, and splash them with his tail every few minutes! They have an amazing aim in doing this. I was lucky as the tetras at some point laid eggs on the side window: The next video shows both the splashing, the eggs up REALLY close (each eggs is only 0,2 mm in diameter!) and the eggs getting splashed:

Some longer closeup video of the actual eggs:

After three to four days the eggs hatch. The baby fish start their lives with an 8cm daredevil drop into the water! That is like base jumping without a parachute considering they are only 0.3mm in length. When you’d compare that to a human, it would mean that a new born baby would drop about 145 meters then hit the water 😛

Once the babies have hatched, they are very small fish that hide between leaves and roots of water plants:

Baby of a splashing tetra

And in real closeup:

Closeup of a splashing tetra (Copella Arnoldi). These fish are only about 0,3mm long right after they hatch!