Advice on stocking of my tropical tank

BoxingFish97 · Jul 18, 2026

Hello everyone, New too the world of tropical fish and is going well so far. I have a 160L tank, Stock I have currently is 10 congo tetras, 2 pearl gouramis, 2 gold african dwarf frogs.I am planning on getting a leopard frog pleco in a few weeks. What im really asking and am getting mixed advice is is there space for 1 more group/pair of fish to add to that group and if so what would you recommend.

Thanks!

Naughts · Jul 18, 2026

Hello and welcome

Do you know the GH, pH and KH of the water? And the temperature range you are keeping the tank at?

bgarthe · Jul 18, 2026

Yes….welcome to TFF.

In addition to the request for the water parameters, please describe your filtration and WC schedule.

My gut feeling atm says you’re maxed out for a 42g/160L tank. As you might suspect, I love Congo Tetras and ten of them are pretty active and would surely benefit from having a 4’ long tank for swimming purposes. The Congos and Gouramis alone are going to be pretty big and have a large bio-load for that tank imho. Sorry, but I have to be honest and suggest you do not add more. Instead, focus on making the stock you have flourish by providing mega filtration with very regular WCs.

Since you asked…..If it were I, I would reduce the ten Congos to five or six and put in several smaller bottom dwelling fish for cleanup. Having a lighter bio-load will make maintenance easier and occupants healthier.

BoxingFish97 · Jul 19, 2026

The KH is 13 but the water where im from is notoriously hard water.My pH is 7.5,GH is 150 ppm (8-9 dgh),The tank is 98cm wide by 44cm tall.Temprature of the tank is 26c.

I would be changing water by 25-30% weekly in the long term and current filter is Oase Bioplus 200

Naughts · Jul 19, 2026

150ppm is not as hard as I thought you would have there. My concern was that the Congo will not thrive in anything but soft water; and as the group dwindled, their propensity for fin nipping would increase and threaten the gourami. If you can maintain a group of 10 they will be more civil.

I concur that a longer tank would be better for the Congo, 120cm+.

The congos are active, yet the pearls require a sedate tank with slow water. The frogs add another complication as any disease treatment would kill them so new additions ought to be quarantined.

If you were to increase the water changes to 75% a week you could shoehorn another group in but small fish could eventually get eaten by the Congo. For “middling to the lower end of hard” water your options are limited, maybe 6 pristella tetra or cherry barb if they interest you? But if it were me I’d just add the (QT’ed) frog pleco then leave it for a while and see what thrives.

Live plants assist water quality in heavily stocked tanks.