hi im posting my problem to get some help hopefully, i am very worried i have a six week old aquarium and two weeks ago i introduced two common clowns and a blood shrimp, all was fine for a week until the gauze fell off my trickle filter inlet and a clown went down and died, i repaired gauze and got another clown but ever since i have they wont pair up and neither will eat, one of them looks healthy but the new one i introduced lookes iller every day his face looks very sunken in but no visible skin problem i have tested the water and the ph has been stable and 0.1 nitrite is present but have been told this is a safe amount! im stuck and could do with some help thankyou!!!!!