I'm not saying any of it to be mean Nicole, but I would hate to see you end up paying and maybe having it cause you financial trouble in the future. A 90gallon setup is very expensive and takes a very large filter etc. Three tanks is a LOT of upkeep and not cheap. I would just keep them in the tanks you have for now, if you get a good filtration system for the larger tank, you can safely keep them in there short term, hopefully until a pond is built in the spring. Investing so much in a temporary housing for fish that weren't even yours to begin with will hurt you in the end, I truly beleive that. I don't know why the landlady went and bought MORE fish for you to have to take care of...that doesn't make a lot of sense, but if you invest in a high quality filter, like someone suggested, they will be better of for the short term while a pond is built, and it will be less expense and work for you. I know you are new to fish, I had many tanks at one point, as well as many bettas in other tanks, and it got horribly expensive to do properly, and a LOT of work. I hate to see you saddled with something that dififcult when you are just starting to get back on your feet. I say it out of concern not being mean.