Apistogramma nijsseni jumping?

[Thotta]

Just found my ap. nijsseni all dried up on the floor. Is this common? I had a top cover but the corners were open (only a small opening...).

 

[A Timbers Fan]

I've seen A. atahualpa jump before. Any fish will jump if it's startled easily (most common reason).

 

[TCMontium]

Yes. Any fish might jump, especially if they are confused and scared because of being new to the aquarium or chased by an aggressive fish or startled/stressed from any other reason. They usually swim fast towards the surface and when they hit the glass, they follow along until the corner and after that the most convenient way to go further away is upwards... This is why people find dead fish on the floor even when there is a cover on top, but there are openings on the corners for external filter hose, air tubing and cables etc.
I stuff the corners with filter sponge that I cut in the shape of the opening. If there are openings in anywhere except the corners, then most fish (probably) won't jump from those, but "jumping" fish like hatchetfish and killifish might jump anywhere. It is best to close any openings big enough to fit a fish.

 

[gerald]

Corners are exactly where fish are MOST likely to jump. I use corrugated plastic signs (FREE if you salvage them after election day) cut to fit in the places that the glass top doesn't cover. If you cut it the right way, the channel along the edge of the plastic will fit over the edge of the glass.