The Y. Modesta Loach looks a lot like the the Red Tail Shark, but you need to keep at least three of them and they grow to seven inches. Maybe not as aggressive towards tankmates, but probably a little big and boisterous for a 40-gallon. I keep four Modestas. Great, active scavengers.
IMO, Modesta need a group of at least twenty. And they can get to ten inches long. Definitely not for a 40.
On the topic of loaches how long will it take for the Yoyos to reach max size? Theyve been growing slowly but I’ve seen some at stores that are pretty massive. I’m starting to think that 40g may not be enough space.
They may take two years to get to maximum given the right diet. They need lots of live food, brine shrimp, ghost shrimp and snails.