Zebra Danio Getting Pretty Underweight 29 Gallon Tank

Hi, one of my zebra danios is not eating. He is the only male of 5 zebra danios. I can't get the parameters. The temp is 74. He looks like he is sucking in his belly almost. Yesterday he ate 2 flakes. Today he ate none. He is almost always hiding in his log. I have a temporary holding tank available if anyone thinks I should move him in there for feeding.
He also eats like crazy sometimes

 

If the gaunt one develops scoliosis, that could mean fish TB. Please avoid putting your hands in the tank, use gloves, and wash well after handling anything related to this tank. Do not share nets and/or cleaning equipment with other tanks. 70% rubbing alcohol in a spray bottle will come in good use as you can use it to spray down all hard surfaces. Zebra danios are notorious for mycobacterial infections.

 

What exactly is fish TB? Why shouldn't I put my hands in the tank is that making my fish sick? or will it make w=me sick? And whats a "gaunt"

 

"Gaunt" is a hollowed out look. The chest will appear caved in no matter how much the fish eats. That and late onset severe scoliosis are the hallmarks of fish TB. So watch your fish closely in case this happens. Hopefully, it will not. Fish TB is caused by Mycobacterium marinum, which I've had the misfortune to encounter too many times along with other mycobacterial infections.

It is generally a good practice not to put bare hands into any tank as people who don't live in the tropics don't understand that warm water can harbor a multiverse of bacteria, mycobacteria, and other unseen organisms. Aquarium granuloma is not easy to get rid of, and fish TB is something that fish keepers just have to live with when it shows up. Keeping the water pristine and feeding well can help some fish live with disease as carriers.

The good news is that 70% rubbing alcohol and vinegar are two common household items that destroy mycobacteria on non-porous surfaces, and they can help a lot in containing the infection.

 

What exactly do I have to do? Please give me steps or something. I forgot to tell you, all of the other fish are fine.

 

At this point, just keep this sick ones in a hospital tank and observe him. If he gets better, then return him to the other tank and feel very lucky. If he gets the disease, then put him down in a cup of tank water with clove oil.

Please don't add any more fish to the big tank until you know what's going on with him. If you must reach into the tank, you can get a pair of pond gloves or get a box of disposable ones from the drug store. If you must put bare hands into the tank, check for any cuts or damage to your skin first as that's how the mycobacteria get into your system--assuming you're not putting your face into the water Like I said, this is a disease that can be lived with although it's a real drag. And don't believe people that try to sell you antibiotics. This is a very drug-resistant disease. I did the antibiotic treatment some years ago, and after months of work, only 50% of that particular tank survived but then ended up succumbing to other issues that took a long time to become observable. Sigh.

This is why I don't buy from LFS in general. Too many different tanks and filtration systems along the way mean that fish have encountered a *lot* of pathogens. If I buy direct from a breeder, there can still be inherited pathogens, but at least it's not like looking for love in a bar...

 

Here is a picture of him

 

His stomach looks bad. I've never had a fish bounce back from this shape. Keep an eye on him and see what happens to his back. It could take days or even months. Fish with mycobacterial infections can linger.

 

I don't have a hospital tank. What should I do? I have a "temporary holding habitat" but no supplies and it's not cycled.
Also it's been like this for awhile now, it hasn't just started.

 

What are your water parameters? You'll need to purchase an API Master Test Kit if you can't get them. Tank size? Is this danio smaller than its other tankmates?

I wouldn't call this fish TB. Seems more like an internal parasite. Easy to treat with medicated food, but I'd treat the entire tank rather than this one fish just in case. Just one scoop of Metro+, five scoops of Seachem Focus, and a few drops of water will do. You can freeze this mixture and use it until it runs out. It is preferred to use it for 10 days, twice a day. However, please answer every question before treating this.

 

At this point, it's hard to diagnose. You could go the route of assuming a parasite and medicating everyone, and that may work. Again, I prefer a hospital tank, but if that's beyond your means right now, I understand. In that case, you could euthanize this individual. Some will judge me harshly for even mentioning that this option even exists. I once got a fish that was at about this stage and stupidly kept him, ending up with TB in the entire tank.

 

I'll get my parameters ASAP. Yes, he is the smallest. Tank size is 29 gallons.

 

I can't euthanize him, he's my little brothers favorite fish, He'd kill me, I also wouldn't be able to do it, I can't imagine actually ending something's life on purpose. I know most will judge me for that, but I like to let nature take it's course.

 

All right. Chances are it’s getting bullied by the others because of its size. Do you see it getting chased/nipped a lot during feeding?

 

Not really... But he seems hesitant to eat.

 

All right. Just keep an eye on him for now. Maybe put him in a breeder net until he gets fed well.

 

Ok.. and what's a breeder net?

 

It’s just a little container made of netting material for fry to live in temporarily.

 

Any idea what to do to stop the bullying?

 

I would separate the danio until it gets big enough to fend for itself. You’d be able to get it well fed as well.