Red Tail Sharks keep dying in just day or two

[quarterback13]

I have a 72 gal. tank . temp. is 80 degrees, ph=6, amonia= 0, nitrite=0
nitrate=80

I have 2 lg. tri colored sharks. 2 lg.silver dollars, 2 clown loaches and 5 lg. angels.
My favorite fish is the red tailed black shark but I had one for a year and it died one night and since I have tried to add a new one 6 different times and each had died within a few days of introducing to tank. All above fish have been in tank for almost a year and are all healthy .
Can anyone give my reason or suggestions.

 

[Juxtaroberto]

Maybe the nitrates? They should be at 20ppm.

 

[Yumu]

I have a similar problem but my nitrates are even higher. I've read that nitrates actually slowly kill your fish by wearing down it's immune system. It's not as quick as an ammonia spike but fatal nonetheless.

 

[felixxx]

murdered by the other sharks?

 

[Juxtaroberto]

murdered by the other sharks?

The most a bala shark would do is stress something out with its constant movement (like discus), but if there were any aggression it would come from the redtail black shark itself.

 

[MonsterMinis]

Nitrates are too high. scaleless fish are in particular sensitive to nitrates. Your current fish are use to the poor water quality. It is unlikley that it spiked that high over-night.

This is why regular 25% water changes or more are a key part in aquarium husbandry.

Simply doing a large water change to add a shark to the tank isn't adviseable either. over a period of weeks doing small but frequent water changes to bring the nitrates down imo is the best way to tackle this canundrum. Then being diligent is your waters maintenece.

Cycleing a tank is 1/2 the battle. The other 1/2 is maintaining the water quality.

If steps aren't taken to lower the NItrates your fish will indeed have a much shorter life expectancy, with slow poisoning. And anything you try and add to the tank no matter how hearty will likely die.

Unless I am mistaken your PH being at 6 and your nitrates being 80 ppm.. You top the tank off with water? build-up of nitrates and ammonium in your system is like trying to keep lightening in a bottle.. eventually it will explode, ie kill the whole tank "for no apparent reason".

It's a very common and curable misconception in the hobby.

 

[quarterback13]

Thanks for your help. I think you are probably right about high nitrate. i did a 35 percent water change and will do one weekly and see what happens over a month or so. Thanks again

 

[Fanlie]

I have a 72 gal. tank . temp. is 80 degrees, ph=6, amonia= 0, nitrite=0
nitrate=80

I have 2 lg. tri colored sharks. 2 lg.silver dollars, 2 clown loaches and 5 lg. angels.
My favorite fish is the red tailed black shark but I had one for a year and it died one night and since I have tried to add a new one 6 different times and each had died within a few days of introducing to tank. All above fish have been in tank for almost a year and are all healthy .
Can anyone give my reason or suggestions.

Red tails shark how big size?
Nitrate too high. best keep under 30ppm. me always 5-10pp, do weekly water change 20-25%
you must now water change like 50%. or add plants.