Plant(s) for 3.5 gallon tank

[Bluepepper]

I have a temporary 3.5 gallon aquarium to hold 4 fish while I rebuild my 36 gallon aquarium.  I know it's pushing limits, but was thinking that a plant might help facilitate the processing of biologicals/waste.  Are there any suggestions for a small plant that can thrive in a pebble bottom?

[Fish Folk]

I have a load of Hygrophylla polysperma (Indian swampweed) in a 2.5 gal tank where some annual Killifish breed. Let me go snap a photo . . .

I also have a small "bacto-surge" sponge filter in there. And since I cannot resist showing him off, here's the male Notho (hiding near the top in the photo above)...

[kammaroon]

Guppy grass and any floating plants.

[Rube_Goldfish]

On 9/2/2023 at 7:29 PM, Bluepepper said:

I have a temporary 3.5 gallon aquarium to hold 4 fish while I rebuild my 36 gallon aquarium.  I know it's pushing limits, but was thinking that a plant might help facilitate the processing of biologicals/waste.  Are there any suggestions for a small plant that can thrive in a pebble bottom?

If your only goal is nitrate/nutrient export, then I agree with @kammaroon; floating plants will probably be your best bet. Otherwise, there are lots of small, slow-growing plants that would fit just fine in a 3.5 gallon tank, like a lot of the smaller epiphytes. Mosses would certainly fit the bill in terms of size. And if it's temporary, you can probably get away with just about any plant. What's the lighting like?