I've currently got my spoiled guy in a 10g all by himself. It's been that way for almost a year now, but I saw a pathetic little guy at work who has virtually no tail fin left. I was hoping to take him home and maybe give him 2.5g of the 10. Would Roscoe (the current inhabitant) notice the missing space? There's tons of plants to explore (a couple of massive swords, some moneywort and some scarlet temple).
I've been keeping an eye on the betta at work and the fin rot is gone, and there is evidence of tail growth so he shouldn't be bringing any of that to Roscoe. We currently have him in a larger breeding trap in our 5g betta treatment tank and I wanted to give him the proper space he deserves to heal. Is this a bad idea? Will Roscoe mind 7.5 gallons vs. his previous 10?