Dwarf Neon Rainbowfish Opening/Closing Mouth

I have had 3 dwarf neon rainbowfish in my 10 gallon QT for 13 days. The last few days I started noticing that one of them was constantly opening and closing its mouth. Then today, it started sitting in one spot for long periods of time. It always used to swim around with the other two and they were all very active. The other two still are, but he just sits there opening and closing his mouth. I'm not sure if this is considered gasping, since he isn't at the surface and he doesn't look like he's trying to get oxygen. Just looks like he's chewing or something.

A few days into quarantine, the temps got pretty high outside and the room the QT is in doesn't have AC. I noticed the tank temp was inching toward and even slightly above the top of the green zone. So I put in a spare airstone, slide back the hood, and turned the ceiling fan on. This helped bring the temp down to around 78-80. I've left the airstone and ceiling fan on ever since, well over a week. So based on that, I don't think he has an oxygen issue.

After not being active all day, I decided to test the water to see if anything was affecting him in that sense. The readings were:

pH: 7.8 (this is steady, all my tanks have a pH of 7.8)
Ammonia: 0
Nitrite: 0
Nitrate: 40

I know the nitrate is at the high end, so I'm going to do a water change in the morning. Is this something that could cause him to sit still and constantly open and close his mouth, while not affecting the others? I know it's high, but it's not terribly high. Also, he started the mouth thing a few days ago, and I would assume that the nitrates were probably lower then and got to where it's at now over the last few days. And like I said, the other 2 are acting perfectly normal and aren't doing the mouth movement.

So, I definitely don't think it's an oxygen issue. It might be a nitrate problem, but I doubt it; and I don't know if high nitrates would cause his issue. Does it? But I'm thinking it's something else. I just don't know what that something else could be. Do you?

Thanks!

UPDATE: I just checked on him and now he is at the surface seemingly trying to get air. So maybe it is an oxygen issue after all. I don't understand how that could be though, especially with the airstone and filter flow. Between the two of them, the water should be plenty oxygenated. Also, wouldn't the other fish be doing the same thing?

 

It sounds like what my paradise fish did when he had something similar to dropsy. He would sit at the bottom, then sit at the top, and just move back and forth.

Does the fish look different in anyway? Any roughness around the head, like the scales aren't laying down quite right?

 

It sounds like what my paradise fish did when he had something similar to dropsy. He would sit at the bottom, then sit at the top, and just move back and forth.

Does the fish look different in anyway? Any roughness around the head, like the scales aren't laying down quite right?

Nope, looks exactly like the other two, except with a motor mouth.

 

One the website:

there is a link right on the homepage to a Rainbow Fish book. If you click the link it will take you to a page where you can download the ebook for free (link is at the bottom of the page)

Anyway in that ebook on the last paragraph of page 66 if I remember correctly (okay I actaully have the ebook opened and although the book page number is 66, the Adobe Reader page number is page 82) it states that "nitrates are reletively harmless unless the levels are very high". So I do not think that is the problem.

If it was a lack of oxygen in the water, then one would think that the other two Rainbows would be doing the mouth thing also, so I do not think that a lack of oxygen is the problem.

Now for the bad news, I've had a couple of Rainbow's behave this way over the years and it never ended well. I kinda wonder if it is a gill problem or something (possibly gill flukes) that makes the fish unable to get the oxygen out of the water.

Sorry I couldn't have better news or be of more help.

Best of luck!

 

Thanks jdhef for looking that up for me!

Are flukes treatable? Are they contagious?

He's still at the top with his mouth right at the surface but he is moving around quite a bit. It almost looks like he's skimming the surface, like there's food or something.

I did some research on flukes and it looks like fish with flukes will start flashing to scratch their gills, and the gills will get inflamed and red with mucus secretions. He isn't flashing and I don't see any of those visible symptoms. If it is flukes, maybe he isn't at that stage yet? Or maybe it's something else?

I also saw that Prazipro is a good medication for flukes? Should I get some and dose the tank (according to instructions) before it gets worse and before the other fish get it? I saw that some people even use this as a preventative medication for new fish or in QT.

 

Well he's dying now. He was just floating through the water, upside down, sideways, every which way. His mouth and gills are still moving, but I'm afraid he won't last much longer.

I put him in a tupperware container of tank water and have it floating in the tank. He's just laying at the bottom of the container, gasping. I don't have any clove oil to euthanize him. At least he won't be picked on or bothered by the others while he passes on.

 

I am so sorry to hear he took a turn for the worse.

 

I am so sorry to hear he took a turn for the worse.

Thanks. He's gone now. So far the others are acting like their crazy selves, so hopefully it was an isolated problem.

 

I've never had that condition spread to the other fish, so hopefully you will not either.

BTW, suggesting that it was gill flukes was just a shot in the dark, I really do not know what causes that problem. But if you figure it out, let me know.

 

While in my years of breeding dwarf neons (m. Praecox) I saw this happen a few times it never seemed to spread among the group and I was never able to figure out exactly what was causing it. I assumed that it was some sort of environmental issue where perhaps a parameter got close to the acceptable range (a little too warm, etc) and a weaker fish succumbed where his or her stronger tank mates were unaffected.

On a side note were the three in quarantine on their way to a bigger school? While a few are nice they are far less stressed (and even more stunning to watch) in larger numbers. A grow out tank with a hundred 3/4 inch long juveniles is quite the sight.

 

Yep, they're to join two already in my main tank. Will be 4 rather than 5, though.

 

Assuming the others don't show any similar problems I'd just assume you happened to get a bad fish. They're pretty hardy in general so it shouldn't happen often but sometimes these things just happen.

 

Assuming the others don't show any similar problems I'd just assume you happened to get a bad fish. They're pretty hardy in general so it shouldn't happen often but sometimes these things just happen.

For the sake of the others, that's what I'm hoping.