Platy Question - illness

[Fish Al]

Hello there,

I am new to this website; however, I have had a small tank for a couple years now. I stick with easy to care for fish, including platys. I had two red platys breed in my tank, and now have a question about one of my juvenile fish. This particular fish is very light in colour, and always has been. The only one of about 6 fry this colour. However, in the last week this fish has been less activity than usual, and is developing black spots. He is moving around the tank, but spends time inactively in my tank's plants quite often and I am worried it may be ill. I don't think he has been eating in the last day or so, and would like some advice ASAP. If I can fix him, I would love to do that quickly so he isn't suffering and it doesn't spread.

 

[Fish Al]

Here is a picture of him, you can see the black spots on top of his body. Not sure if this is part of an illness, or just him developing colour but his inactivity is concerning me. I thought the two may be related.

 

[arcab4]

welcome to MFT! well..hmm...that's a hard one to figure out. based on the picture it looks healthy. the spots i think are just natural in my opinion. could he be a she perhaps pregnant? i had pregnant guppies rest in the decor in my old tank.

 

[Fish Al]

This little one is actually male, and I do have a female in the tank that is pregnant, and I have a couple fry in the decor as well. This one little guy just concerns me because he doesn't come out at feeding time like the other fish. I wasn't sure if the spots had anything to do with this, but the colour seems to have just come on in the last little while so I thought it might be related, perhaps not. Other than that he doesn't have any other signs of illness, his fins are in good condition and I can't see any other spots or indicators... All other fish seem healthy - I have paltys, two albino cats, and two guppies. 20 gallon tank.

Thanks!

 

[FreshyFresh]

Looks like a cute little male platy. What size is this tank and do you measure for ammonia, nitrite and nitrate? What is your weekly water change amount?

First thing I'd do is measure your water parameters. If you don't do water changes, which is a very bad thing in the long run, I'd do daily 20% water changes for a week, then a 50-75% once weekly depending on your stocking level and nitrate creep.

 

[Fish Al]

I do water changes generally once a month, less than 50% though. I haven't tested the water yet because no other fish seem affected but I guess that is a great place to start. Ill be able to do that tonight. The size is 10 gallons (I made an error above and said 20).

Thanks !

 

[FreshyFresh]

Even just a few platys in a 10g are going to require the tank have weekly water changes. Given you've only been doing 50%, once a month, nitrates will be extremely high in that tank. High nitrates very much weakens fish's immune systems and makes them easy targets for health issues. The general hardness, carbonate hardness and pH are likely different between tap and tank water now, so you'll have to go slow at first with water changes. Like said, ~20% per day for a week, then one 50% to fin level change per week. You really should have an API master test kit and get a read on your water params. Ideally you keep your nitrate creep such that it doesn't exceed 20ppm over a 7 day period. If you do a 50% change on a tank that's at 20ppm nitrates, it will reduce it to 10ppm, etc...

 

[CAPSLOCK]

To me the black looks like just coloration. You said he is still a juvie - about how big? Could be a genetic issue if he is still pretty small (developing) and no other fish are affected. Ie, something internal that is abnormal and now starting to show as a problem. Or is starting to be a problem combined with rising nitrates / declining water quality as the juvies grow, eat, and excrete more.