My fish are dying slowly

[N_F_S]

Hello,

I'm writing because I'm very lost about this problem.

Before start with the problem, I will post the main tank information.

Tank

• 170cm long x 50 cm wide x 60 cm tall
• 510L

Current Stock

• 4 Guppy Endler
• 4 Guppy
• 15 Tetra Cardinal
• 6 White Fin Tetra
• 10 Black ghost Cardinal
• 10 Otocinclus (already lost 2)
• 10 Corydoras Sterbei
• 10 Corydoras Julli (already lost 1)
• 6 Corydoras Panda (already lost 1)
• 3 Corydoras Black Venezuela (already lost 1)
• 1 Garra Flavatra
• 20 Amano Shrimp
• 20 Red Cherry Shrimp

Maintenance:

• During 1st mouth - 60% water Change every other day
• Next 2 weeks - 60% wc every two days
• Next 2 weeks - 60% wc even 2x week
• After 2 months until now - 60% wc 1x week

• Never clean my bio media (sachem Matrix) and 1 bag Seachen Purigen, to avoid lose beneficial bacteria in the first months
• Cleaning Pre Filter Sponges every other week

Water Chemistry - Since I introduced fish, ammonia are always 0, nitrite 0 and nitrate 5 during nigth ate the end of the day (reach 10 after add ferts).
PH - 6,6
KH - 3
GH - 5

I need to dose Tropica Specialized when Nitrate is 0. Since Tropica Specialized has nh4no3 (ammonium nitrate), when I dose the week dose (20 Pumps), I have NH4 0,25 for 2 hours, and 0,15-0,2 nitrite 6h before all reach 0 again.

Now, the problem. All my Corydoras are acting strange, with a pale or skin deformation and fin rot, and keep dying.

My last introduction was 4 black Venezuela Corydoras and 10 Sterbei 2 weeks ago.
One day after the introduction of black Corydoras, one of them died (first stoped on the bottom and before died, started to swimming in circles and spinning without direction). 3 days after this, all my active Corydoras started to lay down on the bottom, most of the time, and only active during feeding or right after a water change.

In the first week or so, I lost 1 Julli and 1 Sterbei, and didn't see any external sign in any fish, only the strange behaviour of the Corydoras laying on the bottom most of the time. After one week, some of the corydoras has pale skin and as are losing skin and one And with strange skin too.

My lfs suggests 2 weeks of half dose (because corys and plants) of typical salt treatment (2 tbsp to 20L), and Myxazin. I start the treatment, but still losing fish.

Dead by now:
3 Tetra Cardinal - With white skin on tail
1 guppy - No external symptoms
2 Otocinclus - No external symptoms
5 Corydoras - No external symptoms

Today, I have spotted two Corydoras in bad shape, and for the first time, with real external symptoms.

At the moment I have already finished the 5 days treatment with Myxazin and 7 days with salt.

I don't know what to do more. Any Help?

Some pictures attached.

 

[mort]

Hi, I think treating with myxazin is a good start as the cardinals tail does look like it's bacterial. Unfortunately cories, because they can get abrasions easily from the substrate, also get bacterial problems easily and those pale patches could well be signs of a bacterial issue. @alto is very knowledgeable in this area so will hopefully step in and help out.

I know standard advice is to half dose these fish with meds due to their sensitivity but I've always thought (even if I would half dose as well) that a half dose might not take out what we want so doesn't solve the problem. In the case of bacterial infections you really need to wipe out as much of the bacteria as possible for the fish to begin to recover and I'm not sure if it might be worth slowly raising the dose until it's nearer a normal dose. I wouldn't do this until someone else advises because the reaction you have seen of circling and spinning can often be attributed to medications.

 

[Barbara Turner]

Am I correct in thinking the tank is only a 2 months old.. That's a lot of fish early on even if it is a large tank... Definitely don't buy any more fish.
Although salt will help the fish it won't do your plants any favours. I would do 40% water changes twice a week (treat with seachem prime)
I would also dose the tank with seachem Paraguard as this will treat most fungal/bacterial infections.

You often lose a few fish when setting up a new tank, I would have started with just the guppies, there pretty bombproof.

 

[Tim Harrison]

Looks like neon tetra disease.

Account Suspended

• Never clean my bio media (sachem Matrix) and 1 bag Seachen Purigen, to avoid lose beneficial bacteria in the first months

I doubt it'll become a problem, but a dirty filter might.

 

[Barbara Turner]

Looks like neon tetra disease.

It does look like it but, I thought it only affected Neons, Not cardinal tetras. The strain I had didn't transfer across

 

[Tim Harrison]

It's something of a misnomer; sadly it can infect many other species and not just the tetra family.

 

[RudeDogg1]

have you tested for ammonia, nitrite and nitrate?