Help.. Sick Cardinal Tetras

[Fishyfishlondon]

Hi!

I’ve recently set up my first new fish tank. It’s been up for a few weeks and had 4 gold cardinal tetras and 4 zebra danios as the first fish.

Within a day or two 2 of the tetras died without showing signs of illness. The other 2 have remained looking good but now won’t eat. One of the tetras also has damaged fins and it’s insides seem to be going black and I’m not sure why or how to fix?

Are they diseased? The water tested fine and they were acclimatised for around an hour.

I’ve heard that zebra danios aren’t good with the tetras so could it be stress?

Thanks for your help!

 

[FishFish221]

Do the zebra danios seem to be nipping the cardinal tetras?
What is the tank size?
Is the tank filtered?
What are the ammonia, nitrite and nitrate levels? (specific levels, not "good" or "fine")

 

[Adriifu]

What are all of your water parameters?
What's the tank size?
Have you witnessed any aggression between the two species?
What's the temperature of your water?
Have you applied any medications to the water?

 

[KimberlyG]

Wow, I am not familiar with gold cardinal tetras, but I have never seen anything like this before.

 

[Fishyfishlondon]

Yes they do sometimes nip and chase the tetras.

The nitrite is 1ppm and the nitrate is 20ppm. I don’t know about ammonia.It’s a 125l with fluval u3 filter. I use prime as water conditioner and dosed with stress coat today.

Thanks

Water is 25 degrees and I haven’t applied any medication (only stress coat)

 

[Adriifu]

This looks like a mixture of ammonia burns and fin rot. I would do a 50% water change to get nitrites and ammonia down as well as an addition of Fungus Cure for the fin rot. The medication will lower oxygenation, so try adding an air stone to prevent this. You also need to move the zebra danios to a separate tank or return them if possible, as they may be causing the fin rot.

 

[Fishyfishlondon]

Thanks Adriifu, will try tomorrow and let you know how it gets

 

[Adriifu]

Thanks Adriifu, will try tomorrow and let you know how it gets

No problem, love. Tomorrow may be too long for your tetra, so you may want to start very soon. Anyway, good luck!

 

[Brittni808]

lots of water changes!! firm believer in that no chemical is better for fish than clean water (until your issue resolves)