My Tropical Fish Keep Dying Plz Help!

[newtofish1]

hi there to any1 that can help.
i bought a new fish tank 6weeks ago, it is 4ft 200l. everytime i put fish in it i do it the correct way. i have spent over £90 on tropical fish and they dont seem to last over night they keep dying! the filter is workin the heater is workin the tank is sittin a correct temp and i am feeding them. on the gravel there is dusty fluff stuff i dont know what this is? i have had the water tested and its perfect! can any1 help? thanx

 

[dipsydoodlenoodle]

Did you cycle your tank? If you didn't when you add the fish they'll make ammonia and the filter won't be able to break down the ammonia and it can be fatal to fish.

Also when you add your fish do you add a lot or a few?

Edit: I've added the link to fishless cycling to my footer; have a read of it.

 

[roadmaster]

hi there to any1 that can help.
i bought a new fish tank 6weeks ago, it is 4ft 200l. everytime i put fish in it i do it the correct way. i have spent over £90 on tropical fish and they dont seem to last over night they keep dying! the filter is workin the heater is workin the tank is sittin a correct temp and i am feeding them. on the gravel there is dusty fluff stuff i dont know what this is? i have had the water tested and its perfect! can any1 help? thanx

Has the tank cycled? What dechlorinator are you using for new water added during water changes? How often do you perform water changes? What are test results for pH,ammonia,nitrites,and nitrates? How are fish being acclimated? What types of fish are you stocking? What is temp in the tank?
What type of filter is on the tank? Have you replaced or cleaned the filter material recently? What other fishes are in the tank? What chemicals or medications ,or other products are being used in the tank?
Answers to these questions will maybe help others to provide you with some help.