I’ve seen this a few times over the years. Generally, it happens when I buy some new fish. And because they’ve just gone through the trauma of being shipped across the country in a dark box for two days, and thrown into completely unfamiliar surroundings, they hide at the back of the tank.
I knew I wasn’t the first and only person to deal with this. A few weeks ago I was reading a fish seller’s feedback and noticed someone complaining about how disappointed they were that the fish just hid at the back of the tank. And about two weeks ago I bought some fish, which had a particularly bad case of this, and it had me wondering if I could solve the problem.
I was dealing with two pairs of guppies, two males and two females. The males didn’t have any anxiety issues at all. The females were both cowering in the back corner, facing away, and swimming into the corner (going nowhere fast). I decided to add a ceramic bridge ornament to the tank to give them a hiding place. At least it would give them a chance to relax instead of being in scary open waters.
Then it occurred to me, guppies are very social fish. If you watch guppy fry, they actually interact with each other. I thought I could use this as a way to snap these fish out of it. If a couple other guppies were added to the tank who weren’t stressed at all, and seemed perfectly happy, it might wear off on these.
Now it’s not usually a great idea to add your own fish to new fish right away. You can sometimes transfer disease this way. So I don’t recommend doing these experiments with your best fish as a precaution.
I started by adding two of my males to the tank. This had no effect on the two scared females. In fact, none of the males would even go near the females. This was after leaving them in the tank for a day or so.
I then wondered if adding some of my other females would be the actual social switch. Because female guppies seem to be annoyed and distant with males, probably from constantly trying to get away from them. Maybe female guppies have social connections only to other female guppies? (But “tolerate” having the males around?) So I added two happy-go-lucky females to the tank.
Within a few hours, one of the scared females moved into the main group of guppies, no longer scared. By the next day, the one in the photo above was fully socialized and out of hiding. The males were at this point chasing both females. They are now fully integrated into their tank without any fear when I walk over for feeding. As if it never happened.
So if you have this problem with your fish, this might help correct the problem.