That school of rummy-nose tetras in your big tank looks awesome! This is how tetras should be kept; I alway feel bad for these fishes when they are kept as pairs.
I agree, this is my 4th tetra school, 2nd rummynose school. I've always started with 15-18, but as they dwindle I end up with odd groups.
My first school or Cardinals was purchased as adult fish in 2018 and that was a mistake as I had several die off in the first year seemingly of old age. Had about a dozen for several years, then I got the silver tips as adults in a group of 15 from a member of another forum. She originally had 30 and they had started to die off.
My first juvenile school of rummynose brought a nasty nasty case of Epistylis, prompting the build of my super uv sterilizer that cooked through itself in about 3 years use.
After setting up the 125 I had an odd group of a few silvertip, half a dozen rummynose, and a super senior citizen cardinal that's been hanging with the rummynose on his own for about a year. I'm pretty excited to have seen all these species and make a good decision on bringing these back up to numbers I couldn't keep before. So far they all seem really healthy, if the school matures nicely I might bring another school of 20+ Harlequin Rasbora in, they're the only cyp I've ever kept but watching them breed was definitely one of the coolest swimming displays I've seen, again though, I purchased those as adults and only got ~2 years out of them, at the time I wasn't good enough at pH regulation to keep the eggs healthy.