Hiya, I have been cycling my fish tank for almost 6 weeks now and have had about 10 fish die during the process so we added safe start to the tank. but gave done a water test today and ammonia and nitrite are at 0, PH around 7.4 but nitrate is around 40/50 ppm. I have read that the production of nitrate indicates the near end of the cycle. However, we bought a parrot fish and a red spotted Sterenum today but they are just lying at the bottom of the tank within shaded areas, so we did a 20% water change and added safe start again. But there is still no change in the fish behaviour. Also a few days ago we bought 2 green Sterenum but these both died over night. I'm really confused as to why this is happening if the ammonia and nitrite are at 0. I would appreciate any advice anyone would be able to provide.