I need help with my 20 Gallon Tank!

[Byron]

It would be advisable to pin down the GH number. Small tanks (a 20g is quite small when it comes to fish) is that the more suitable species will usually be nano or small-sized fish, and often these are wild caught, or being small have much less adaptability when it comes to water parameters. Your local water authority web site might have the GH information.

The pH is important but less so, and as it seems to be on the acidic side, and assuming we are actually dealing with softish water, this should pose no problems.

Temperature is the other important parameter and you will need to decide on, based upon the fish species selected. Many will need more or less warmth than some others. And again, when dealing with the small-sized species temperature becomes even more important because temperature in all fish drives their metabolism and small fish have a higher metabolic rate than larger fish so this can be quite significant.

Aside from the above, I agree with others that a male Betta should never be forced into a tank with other fish. And rummynose tetras need a longer tank. But if your GH is on the soft side, your options are many for this tank.

 

[utahfish]

Ive kept a shoal of 8 rummys in a 20 gallon.
They are sensitive fish and form tighter shoals than alot of tetras.
They require really soft clean water.

They will do better in a longer tank but a 20 long is 6 inches shorter than a 3ft tank.

If one has soft water a good center piece fish would be a dwarf gourami which occupy more mid top levels or a bolivian RAM that in the wild is a solitary fish except in mating season. They are very peaceful dwarf cichlid and a shoaling tetra like rummy nose help them feel safer.
Bolivian RAM is also a bottom dweller as its an earth eater so would need sand not gravel if gourami gravel is fine.
Id also suggest getting another similarly shaped shoal of tetra. Having another shoal of similarly sized fish help the rummys and the other shoal feel safe as their presence signal to eachother the absence of predators and they will also loosely shoal together. Ive had neons, black neons, glow light tetras, von rio flame tetras with rummys. Penguin ,embers ,green neons and emperor tetras haelequin rasbora or dwarf pencil fish,would also work. All these fish can do well in same temperature as well 76-82 Rummys id suggest keeping them closer to 76 than 82.
If you have hard water disregard everything because all the above mentioned fish are soft water fish and hard water will be detrimental to their health.
Also all these fish appreciate and thrive with live planted tank rummys need open swimming space though along with plants.

 

[JuiceBox52]

You could do rummy nose in a 20 long but not a standard 20g

 

[JuiceBox52]

But we do need the GH first