Tiny Goby

DustyBootsAZ · Oct 28, 2025

I finally added some fish to my biocube 32. I’ve got a yellow clown goby that is really small and hanging out against the back of the tank. I’m worried he might get through the slots into the overflow. Anyone have any problems with that? Any way to prevent that?

Biokabe · Oct 28, 2025

Yes, fish can get through those weirs if they're small enough. Most aren't, and most aren't interested in going back there, but some of those gobies are absolutely small enough to make it through.

Short of putting some kind of fine mesh over the weirs, there isn't really a way to stop them. And putting that mesh there can cause issues, especially if it gets clogged up with detritus from the tank. I don't think there's a big risk of your fish going back there, but I say this as someone whose fish once hopped in the overflow and somehow made it to the sump, so...

P-Dub · Oct 28, 2025

A fish, particularly a small one, is always susceptible to going over the falls. If you can place a mesh in front of, or better yet, pinned to the backside of the weirs that have smaller openings than what the fish can pass through, but not so fine as to present a clogging issue, that is what I would do.
https://www.etsy.com/listing/907409...bgH1zvLz5T-5w5ZlnE06rqEmNIPRj0OxoC-_sQAvD_BwEThese fish have the habit of doing exactly what we hope they don't do. As @Biokabe stated, I, too, have had fish in the sump.