Mini fish in a Monster tank. Hypothetical Scenario

[ichthyogeek]

I was reading through an old fish book of mine, and came upon this small (paraphrased) quote: "A small fish in a large tank wouldn't need much in terms of water filtration, it wouldn't even need water changes!" Obviously that's not true. But, it did raise the question of having tiny fish in a giant tank. I'm talking about fish with maximum sizes of 1.5" like D. tinwini or D. margaritatus, even C. pygmaeus, in large (greater than 100 gallons) aquariums. This popped into my head. Thoughts?
100 gallon aquarium
20 D. tinwini
20 C. pygmaeus
quartz sand substrate
Pistia stratiotes/Myriophyllum aquaticum
Daphnia
Copepods
blackworms
slate plates

The tank would be setup so that greenwater was brought up first, followed by daphnia, blackworms, and copepods. After that, water lettuce or Parrot's feather (depending on shallowness of the tank: Pistia if deep, Myrio if shallow). Followed by the danios and corydoras. Eventually, they'd breed to stable proportions, as long as food was added in the form of flakes, more live food, or greenwater, right? Water lettuce always likes to shed its roots for me, providing food for blackworms, which in turn, feed corydoras. The roots that remain, create a wonderful breeding ground for danios. Kind of like ponds, but more controlled (if control is possible). The small fish would be able to be interchanged (say rosy loaches for the pygmy cories). Comments, concerns? I'll say this right now: HYPOTHETICAL SCENARIO. None, I repeat no interest at all in this setup as a physical reality so far. Just posting to learn more such as pros and cons.

 

[HybridHerp]

The only issue is I don't think you can get the tank to be self sustainable because the fish are probably going to eat more than what the tank produces. But I mean it'd be an interesting experiment. I know lots of planted tank folk with larger tanks just have it stocked with a bunch of smaller fish.

 

[azmtns]

This is basically what people do with horse troughs in the summer. Many cattle ranchers out here in Arizona keep livebearers or killifish in their giant cattle troughs to eat the daphnia and mosquito's. The daphnia eat the green water, the only thing they do is top off for the cattle and it goes the whole summer.

 

[Yuki Rihwa]

I stock few fishes 1~2 inches mostly Octocinclus and cory cat in my 125G planted tank, I didn't do any water changes for last 4 years....everything still look healthy and happy (added water each week that lost by evaporation).

 

[jeaninel]

I stock few fishes 1~2 inches mostly Octocinclus and cory cat in my 125G planted tank, I didn't do any water changes for last 4 years....everything still look healthy and happy (added water each week that lost by evaporation).

Can you post a pic? I'd be interested to know what your water parameters are also.