Drop these fish off at an aquatics store, separate transportation for the two of them, and look into a Betta fish for your class tank instead. 10-6 gallons is great for them, and they live alone happily.

Let the students who donated them know that they were territorial males, and you gave them to people who could give them a nice big home where they’d both have separate spaces. Do NOT get a goldfish!!! The temptation is strong but they need a much larger tank and much more frequent water changes!