That will be crazy if most of the polys stay in that bridge cause they think its a cave, them the middle one needed to go up the surface.
Interesting concept!
Vancouver_98683 - where is that? Wow. Crazy to think about how far the fish are going. I wonder how long it takes them to figure it out and if only some will do it when the bridge is that long.
What UJ species specifically do you want to keep, Binge?
Looking at my Del, she is only 8 inches and fairly thick, especially on a full stomach. I would worry about her being able to make the 90 degree turn as she got bigger. If it was straight it might be a different story.
Ornates and Weeksii also get pretty thick as they age. I think Teugs stay narrower in general but we've seen obese Teugs too.
Does it have to be a 90 degree bend? I would err on the side of larger. It would be horrible to find out the hard way that it wasn't large enough.
But I'll be curious to hear what others have to say. I've never owned an adult-sized UJ.
I think it's less of an issue for them, since they're smaller and won't block the whole pipe so the others can't passWell, that one guy in the link did it with Bettas and Gouramis, and they need to breathe air.