Bit of an unnecessarily blunt response there, we're all here to learn and improve as we go and nobody is on here intentionally seeking to do bad by their fish.
They are here for advice, not your attitude.
Yep, let's be nice, please. This is a new member looking for advice.
You are all right, I sincerely apologise for being so harsh, it was out of line, and I should know better by now not to post when I'm having a rough day.
Wow okay, so are my shrimp okay?
I'm sorry I spoke to you so harshly the other day - I usually have a lot of empathy for beginners who make completely understandable mistakes due to the amount of mis-information on the internet - I was not having a good day, but that's zero excuse for taking it out on you, and I'm sorry for that. I hope you don't hold it against the hobby as a whole, most people are really nice and helpful! I usually am too... I hope you can forgive me and let it go.
Honestly in the other tank everyone seems very happy and the betta doesn't appear to bother them. It's densely planted maybe that helps.
Being densely planted definitely helps, and long fin bettas especially are pretty slow and clumsy, as fish go, while WCMM are especially fast and zippy. In the long term though, they do need different tanks with different parameters, and the zippy fast swimming WCMMs need a fair bit of horizontal swimming space.
How large is the WCMMs/betta tank at the moment? Are the plants live plants?
While they may not appear bothered at the moment, fish do release hormones into the water around them. Bettas are a predatory and very territorial fish, and the minnows will be very aware that there is a larger, predatory fish in the same tank as them, without having an escape. Stress is the biggest killer for fish, since stress lowers the immune system, just like in humans and other animals, and chronic long term stress leads to physical illnesses and problems. Since we can't easily see visible signs of stress in fish until it's become chronic or it's too late, the best we can do is try to manage their environment and replicate how they would live in the wild as much as we reasonably can. So solitary fish living alone, schooling fish having enough numbers to feel safe, similar water parameters to the ones they evolved in, etc.
I thought bettas could have some tank mates, apologies for asking.
Please don't apologise for asking! Urgh, I feel terrible for making you feel that way. It's a hot-button topic in the hobby sadly. There are a lot of people who say it's fine, that it worked for them, and recommend different species to try.
I'd say the majority here are anti-bettas in community tanks. There's more of a tendency now in the hobby to try to recreate wild type habitats and biomes, and for natural tanks with live plants and natural decor, rather than plastic and mixing fish based on old school fishkeeping without regard for hard/soft water and schooling numbers. In the wake of the internet, youtube videos of fish in the wild, more scientific studies on wild fish and the aquarium hobby, we've learned more about the habitats the fish we keep come from.
I'm on the solitary betta side based on the fact they live solitary lives in the wild, and are so territorial. There are also a lot of threads here from people posting in a panic because their previously "calm and friendly" betta has massacred their tankmates...
While that's partly the nature of betta fish, I also think it's always worth remembering that the fish we buy in stores are juveniles. It often happens that people think because their fish are fine together for the first year or so (depending on species maturation dates, OC) that all is well, then chaos breaks out once the fish reach maturity, want to breed, and begin tormenting and even killing other fish. This happens a lot with cichlids like angelfish too.
Also I'd like to add that I care very much for my fish and don't view them as decorations.
I'm sorry too for suggesting that! There's nothing wrong with thinking about the colour combos when considering what fish to get, along with the needs of the fish too, of course. Some bettas can live in the same tank with shrimp or snails, as others said. They don't always seem to view them as competition or food. Some bettas do, and will eat shrimp or peck at the eyestalks of snails, and I'm afraid there isn't really a way to tell how nippy your betta would be without trying it out.
Keep an eye on the amanos and see how your betta is with them. Since amanos are pretty big (and very fast when they "leap")! hopefully they'll be fine. If he remains okay with them, then it might be worth trying some neocaridina shrimp with him. They come in all sorts of colours, including some stunning blues! Or you might prefer the red as a contrast to the bettas blue. A word of caution before buying any though, since the blues and other colours tend to be pricy, and that's tough if they become a snack for the betta - if you want to try them, a densely planted tank will give them the best chance of survival, and you might want to do a trial run with a few culls first, just in case!