I would still think a small internal filter could/should be used.A mudskipper tank maybe?
This depends on how you describe successful. For me, a successful tank is one where the inhabitants thrive and I get to mostly sit back and enjoy it. Without a filter, the demand for water changes and my personal worry about the instability of the thing would take away lots of the enjoyment part.I have a 10gal with loads of plants and just a few small fish, and the filter was accidentally off for an entire week and no ammonia ever appeared (all fish were fine). I think as long as you have more than enough plants to take up fish waste you shouldn't have a problem. Try to find nutrient hoarding plants like hornwort (others definitely will have better plant suggestions) and I don't see why you couldn't run a successful filterless tank.
:y220e::y220e::y220e::y220e::y220e:let me get thie striaght...
You just asked us which species of fish can survive the most torture?
Which species can I burn off their gills, slowly suffocating them, and causing their organs to fail, infections to set in, fins rot off- with ammonia- which one will survive this the longest? that's your question?
FISH CAN NOT LIVE IN A TANK WITH AMMONIA. IT BURNS OFF THEIR GILLS AND THEIR SLIME COAT AND IT MAKES THEM SICK AND SUCEPTABLE TO DISEASE AND INFECTION.
You might as well ask which Dog can I beat the hardest before it dies? What type of rabbit can starve the longest without dying?
Now if you want to know if its possible to keep a fish in a tank with enough plants if you will be devoted to enough water changes with a really really really light bioload- so much so that there won't be detectable ammonia in the tank- then ask that and we might be able to help you.