Which of my fish is best for cycling?

Ed: Save yourself the grief and just do a fishless cycle...Normally I would of recommended just moving some gravel and filter media, but you definitely dont want to transfer that black algae...

The best fish for a cycle is the invisible fish.

Just do fishless cycling or my favorite, Bio-Spira. Much more humane and actually faster anyway.

Curtis

Just curious, but what was the rational behind adding co2 to get rid of the algea?

I would imagine that adding co2 was told because if the live plants are plentiful and healthy they will outcompete algae for nutrients, therefore sort of prevent algae. Most likely it was miscommunication as far as "how" exactly the co2 is supposed to be helping.

Can you borrow some filter media from a tank without black algae?

otherwise get test kits move the fish over and test for ammonia and nitrites. When they show up that menas the bacteria can't keep up so do a water change. this may mean daily water changes until ammonia and nitrite test as zero. Lot of work but keeps fish healthy.

Moving over a single fish to cycle with only means your tank is cycled for that fish. So each new fish will only create a new cycle as bacteria competes to catch up with the higher load of waste. Bio-Spira or fishless are the best ways but fishy cyclign works well if you are diligent and don't mind the work.

Unfortunately though Marineland changed the "formula" for Biospria with their last round of production, there is a lot of mixed results now, more leaning toward the not working part. Thats unfortunate because when it was first introduced, it worked awesome, now its really just another con.

NO fish is good for cycling, its cruel to put a fish through that especially when you can use ammonia to cycle the tank.