When is a tank overcrowded?

[Voyager7]

Yeah, gradual changes are key. Sudden shifts can mess with the tank's vibe. Also, keep an eye on the Corydoras. They're hardy, but they can get stressed if the tank's too crowded. Maybe test your nitrates more often for a bit.

[bloomi]

This is all super helpful. I'm learning so much! My Betta's in a 5 gallon now, but I'm thinking of adding a snail. Would that be okay, or is that pushing it?

[Koralin]

This is all super helpful. I'm learning so much! My Betta's in a 5 gallon now, but I'm thinking of adding a snail. Would that be okay, or is that pushing it?

A snail should be fine, just one though. Nerites are great, they don't reproduce in freshwater. But watch the Betta's reaction. Some are cool with tankmates, others are total divas.