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Check this out: I got a bunch of wild Scriptaphyosemion geryi killifish from Jeff. After being in the aquarium for a few days and seemly doing fine, one point , one-by -one, all the killifish started jumping out of the water and sticking themselves on the glass sides of the aquarium. They would stay stuck to the glass sides for up to several minutes before flipping back into the water and then jumping back out after a few seconds. It started with one and then the others seemed to catch on and do the same thing. I've never seen anything like it.
I suspect that the temperature of the water was getting too warm (~78F) and perhaps lowering the dissolved oxygen content to a level unacceptable to the fish (they are said to originate in streams with high O2 content). Species of the genus Scriptaphyosemion are known to be exceptionally good jumpers, able to escape through the tiniest of openings in an aquarium. I've known this, but never considered why they are such good jumpers. Now I think I see at least one reason why - when water temps or other parameters become unfavorable to them, they can resort to literally "flipping out" of the water to get more oxygen in a semi-amphibious manner. I can imagine them flipping into moist leaf letter or sticking themselves onto leaves of overhanging plants at the water's edge and lodging there for a while or even migrating to a better water hole. I now recall that certain species of Rivulus do this as well.
I've lowered the water level, reduced the temperature and added an airstone to increase O2 levels and the jumping behavior has stopped. Pretty neat to observe it though, and was able film the geryi jumpers in the video below.
Also got this rather amusing photo of three of the females stuck to the glass sides, hanging out as if they were "at the beach" or something.
I suspect that the temperature of the water was getting too warm (~78F) and perhaps lowering the dissolved oxygen content to a level unacceptable to the fish (they are said to originate in streams with high O2 content). Species of the genus Scriptaphyosemion are known to be exceptionally good jumpers, able to escape through the tiniest of openings in an aquarium. I've known this, but never considered why they are such good jumpers. Now I think I see at least one reason why - when water temps or other parameters become unfavorable to them, they can resort to literally "flipping out" of the water to get more oxygen in a semi-amphibious manner. I can imagine them flipping into moist leaf letter or sticking themselves onto leaves of overhanging plants at the water's edge and lodging there for a while or even migrating to a better water hole. I now recall that certain species of Rivulus do this as well.
I've lowered the water level, reduced the temperature and added an airstone to increase O2 levels and the jumping behavior has stopped. Pretty neat to observe it though, and was able film the geryi jumpers in the video below.
Also got this rather amusing photo of three of the females stuck to the glass sides, hanging out as if they were "at the beach" or something.