I have several local buddies who do Killies trying to get me into them . I have to get closed topped tanks . I bought one pair at auction a few months back and they jumped out . Two of my buddies raise them in the shallow plastic totes . I will say, very stunning fish
I use this arrangement of the cover plate for killie aquariums.
the disc is only 1 mm less wide than the inside dimension. At the back are 2 small angles, bent from stainless sheet, 0.5 mm thick.
the cover is absolutely tight. Only in the corner is something chamfered for the air hose. There I seal off with foam.
If you use imgbb I can help with that. Super easy to use, and very user friendly 3rd party hosting ime. (Hint: just copy the direct links I'll help you out with figuring out how to do that if you use it.)