What's new

Platy fish rapid breathing

🐠 March TOTM Starts Now! 🐠
FishForums.net Tank of the Month!
Click here to enter!


New Member
Aug 6, 2023
Reaction score
Grimsby, UK
Hi noticed my platy is floating in one place swimming less and breathing rapid. Visually looks fine other than breathing fast which caught my eye. Last week another platy passed after a week in a separate tank and the first symptom of that I noticed was rapid breathing. Again unsure why. I moved it to separate tank and put some melafix in and it was eating but staying at the bottom of the tank rapid breathing. Passed after a week.

What can I do for this platy as I'm unsure what's wrong. I'm due to go away Tuesday for 3 days I've just done a 50 percent water change. Tested the water and everything was in the normal range with testing kit.
Hello. The best thing to do is always perform a slightly larger than normal water change. My philosophy is this: If the tank is less than 30 gallons, you change half the tank water twice a week. If the tank is 30 gallons (you can do the gallons to liters math) or more, then change half the water weekly. If you're not doing this, then you need to slowly work up this point. Always make sure you treat the tap water. Don't feed the fish very often and when you do, just feed a little variety of flakes, freeze dried and a little frozen food. Don't miss a water change and avoid putting chemicals other than the standard water treatment into the tank water.

There could be multiple reasons why such a platy is breathing heavily. If the water parameters are okay, the causes could be lack of oxygen, gill problems or an internal problem.
I feel like we might need more information. The platy that died, did it show any symptoms aside from rapid breathing and lethargy? What's your water temp, and do you have any airstones or other methods of surface agitation? If your water conditions are fine and they aren't showing any other symptoms that might indicate infection, I'd want to rule out a dissolved O2 concentration issue first. Lethargy and heavy breathing are pretty classic symptoms of low oxygenation. Water temp is important too. Warm water holds less dissolved oxygen. If you're keeping your tank on the warm end and you don't have good water agitation, that could be an issue.

Is your tank planted, and if so, do you inject CO2? That can also cause labored breathing if you're running it at too high of a level. Also worth noting that plants consume oxygen at night when they aren't photosynthesizing, which is why it's still good to have surface agitation, even in a planted tank.

If it's not an oxygen problem... Does the platy have any tankmates that might be bullying it? Heavy breathing can sometimes be a symptom of stress as well.
Hi all apologies for a late response we were away. I was surprised to see that our platy was still alive when we returned home and was doing well. This changed quickly and today was The first day I noticed it on the flbottom of the tank again gasping. By the time if walked the dogs it was dead unfortunately. As we have just returned home the water had not been changed since going away but I did do around 60 to 70 percent water change as I knew it would be over a week before its changed again.

I checked the water after the death of the platy and the nitrates and nitrites were high !! Really high so no wonder why it was sick. I feel so sad that this has caused it.

My questions are how in just over a week after a 70 percent water chnage could it have increased so high?

I have a few ideas please tell me if theses are likely and how I can solve them.

I have 140l tank with 3 Cory's, 3 headbanging, 4 tetra, 3 shrimp and around 8 platys maybe more as they keep breeding and new ones often show up.

I have lots of plants but I can't seem to keep them alive they're often brown and wilting. I'm also noticing lots of black fluffy algae growing on them too. Is it black beard I've been trying to do some research. It seems to be all over our decorative items too.

We upgraded our filter it's a fluval one to cover the litres in the tank but it's okay for about a day or 2 then the flow is just dripping and its completely clogged up. I'm maybe thinking this is why the water is so high as its barely being filtered out. When I clean it out I seems to be blocked by lots of brown sludge. Really thick anyone have ideas how i can stop it from blocking
Just to add after I noticed the water was so high I have done about a 75 percent water change and cleaned out all the filters. Anything else I can do to keep the spike down
Here's a pic of the tank showing the black algae growth and my dying plants


  • 20231222_165252.jpg
    345.3 KB · Views: 10

Most reactions


Staff online