My corydoras finally started schooling tight after I added more of them
Had six corydoras for about a year and they always just sort of hung out near the heater, never really schooled, just scattered around the bottom doing their own thing. Read somewhere that six is kind of a bare minimum and they actually feel more secure in bigger groups, so a few weeks ago I added six more panda cories to bring the total to twelve.
The difference honestly surprised me. Within a few days they started moving together as a loose group, foraging across the substrate in a pack instead of each one picking its own spot. Now when one gets spooked and darts off, the whole group follows instead of just that one fish bolting alone. Feeding time looks completely different too, they all converge on the same area and work through the substrate together instead of being spread out across the tank.
I knew the "shoaling species need bigger groups" advice in theory but seeing it play out was a different thing. My tank is a 55 gallon so bioload wasn't really a worry, filtration handles it fine and I kept up with slightly more frequent water changes the first couple weeks just to be safe.
Only downside is I definitely underestimated how much substrate disturbance twelve cories create compared to six. My sand gets rearranged into little dunes overnight now, which honestly I don't mind, just wasn't expecting it.
Anyone else notice a similar shift in behavior after increasing a cory group? Curious if there's a point of diminishing returns or if more is just generally better for them within reason.