Ok so i'm not the best at meaningful names. lol i'm more for cute names, but I tried so here's my names with an explanation as to why I picked them.
I picked Gandolf because he seems very wise and his coloring even resembles that of Gandolf's cloak.
I picked Triton because number one he was a merman and number two he was god of the sea. This Betta also looks very powerful which is why the name suits him. The Betta's gold coloring on his tail also resemble a triton. So there's multiple reasons for this name lol.
Hope this helped :)