I'm planning on growing some plants outdoors. I have a 55 gallon that split a seam, so don't trust it in a house ever again but still wanna use it. So last fall I caulked it up really well so it will hold water. But what I don't want is a misquito farm. Any ideas on what kinda fish I could put in it that would eat them but still be ok with minimal care? The tank will be unfiltered, unheated or cooled. I'll just be doing weekly water changes or changes when needed. I was thinking bettas but I'm afraid they would be to expensive in case they happen to die. Koi or goldfish won't work cause the water may get to warm and they are to dirty for an unfiltered tank. Any ideas?