I used giant danios to cycle mine, after seeding the filter with bacteria. They all lived, until eaten by the piranha.If you cycle your tank using pure ammonia, you don't add fish until it cycled.
If you are cycling the tank with fish in it, you should expect them to die (maybe you will be lucky and they don't), unless you are prepared to do lots of water changes. So in other words, any fish you use, should be considered sacrificial. Or very few, very hardy, small fish until the tank tests free of ammonia, and then add only a few more at a time, and gradually, to allow the ammonia consuming bacterial population to adjust to the new fish numbers.
cycling the filter a week after set up
Hello; This may only be a bit of being picky, but the entire tank is cycled not only the filter. The bb will likely be in the filter and media because there is a good flow of water all the time and ammonia from the fish and other processes will pass by. The bb will colonize all other tank surfaces eventually again by my thinking more likely where there is a water flow. My earliest tanks had no filters at all and the flow was by convection heating. I point this out as there seems to be a line of thought that considers only the filter media to have bb.plenty of biomedia for the nitrifying bacteria to colonize
Hello; I understand the wish to rush to having fish in a new tank but without a source of bb to use up the ammonia any fish will be harmed. The fish may live but I have read that there will likely be damage.any fish you use, should be considered sacrificial
Fx6The importance of cycling cannot be overstated. Larger tanks take more time to properly cycle, but once cycled are far more stable than smaller tanks. As previously stated, adding material from an already cycled tank will speed things up. It is important to have plenty of biomedia for the nitrifying bacteria to colonize. What type of filter are you using?