I'm a teacher in a primary school and am looking for a fish tank to create a calm space in my year 3 classroom. It's will also enable children to have jobs. I will also appreciate some accessories, but until I have a tank I can't really say yes to heaters/filters/air pumps as I don't know what size I'll need. I'm not too fussy about size (although I would like to keep at least 5 fish in it so so not too small) but would appreciate watertight and cuboid rather than spherical. MAny thanks for reading.

Fish tank (New Eltham DA15)