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I have a pair of common BNs and I am going to put them in an aquarium by themselves.

Is a 60cm x 30cm x 30cm aquarium good?
I will not put gravel or sand for easy cleaning, I will put in some caves and driftwood.

About filtering should I get sponge filters or is it better to install an internal filter and 2x airstones?

Your tank is 23.6" X 11.8" X 11.8" or 14 gallons. That is probably a bit on the small side for a dedicated Ancistrus breeding tank, but can work with a pair that gets along without fighting.

Filtration is really up to you (I would prefer a sponge over an internal power filter, but that is just me). Given the small tank size, just make sure you keep up on the water changes.

-Shane

I have kept a pair of albino BN and a pair of red marble BN in both 15gal and 10gal. I have used both a small power filter on the end of a tank and also sponge filters. Power filter is on short side end with pleco cave towards front, similar to sponge filter on opposite side of pleco cave. I do 25-30% water changes weekly for a few weeks and then change to 10% every other week just enough to pull waste from the tank. I alternate algae wafers, shrimp pellets, and whiteworms once a week. My cave is oval about 2.5w x 1.5h x 6l.

and with that tank did you succeed in breeding them?

If we are talking regular common bristlenoses, they will breed as long as you have a pair and the water conditions are reasonable, and temperature between 22-26'C (give or take a bit). They don't need a huge amount of space (but once they do breed, you will need space for the offspring).

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Mats