[cS]

Apologies for the delayed response Carlos.

I used to keep a reverse trio of Parosphromenus deissneri 'Red' in a heavily planted 29G for almost a year. One day after a major aquascape change, they all died. :evil:

During that year, they bred for me twice. The first time, they built a bubble nest underneath several intercrossing blades of S. subulata. The second time, they didn't even build a bubble nest. The eggs were simply deposited underneath an Anubias leaf in a secluded corner. I was not able to raise any fry (I wasn't trying) -- the other fish (or the parents) probably ate them all.

The dGH of my tap water is 1, but I raise it to ~3-4 with CaCO3. pH is ~6.5-6.7. I think stability is more important than a specific pH or softness. After all, I was able to keep and breed Sphaerichthys osphromenoides (chocolate gourami) under the same conditions. I should note that none of the chocolate gourami fry survived to adulthood either.

The licorice gourami's movement is similar to the chocolate gourami: shy and slow, so take that into consideration when choosing companion fish. In other words, they are poor community fish. However, unlike the chocolate gourami, the licorice gourami (1) is not aggressive, (2) readily accepts dry/frozen/live foods, and (3) is not prone to as many diseases.

 

[cS]

Carlos, I do not know if those parameters are too high for the fish. Although expensive, I would test it out with a single fish and add more as necessary. The reason I say this is because IME, they are less sensitive than the chocolate gouramis, who supposedly only live in soft and EXTREMELY acidic conditions. And yet I am able to successfully keep these chocolates and even got them to breed (though the females just spit the eggs out so not a single one hatch AFAIK) in 3-4 dGH & 6.5-6.7 pH water.

However, to be honest, I would caution against your original intention of keeping 6 of these licorice gouramis in a 20G. Despite their small size, they are better suited for larger tanks as conditions are more stable and thus hopefully aid in your success at keeping these fish. Just make sure they get enough to eat, considering the other tank mates you're planning on keeping them with.