Platys - How Long To Newbies Stress?

[amcalab]

I added several (~12) male platy to a newly cycled 29 gallon tank. After 2 days, about 4 of them are showing signs of stress exhibited by clamped fins. All the fish eat well. And no one stays hidden all day, although one of the stressed fish favors hidding places towards the bottom of the tank.

I checked all the paramters and things seem well. No ammonia or nitrite. Nitrate levels low. PH is neutral and steady. Temperature in 79 degrees.

They are no signs of Ick.

Although there is one semi-agressive platy, he mostly just chases another healthy platy about his size. And there hasn't been any fin nipping.

Before I added the fish, I added a one time half-dose of aquarium salt to help reduce stress.

Is this normal for platys when getting used to a new home? Are these fish on a death march or do they recover after a few weeks?

I don't want to throw in any medication for clamped fins because (1) I don't know the cause and (2) I'm afraid medication would only stress the fish out even more. So, right now I am taking the hands off approach...very minimal interaction - only water testing and feeding.

I heard that platys were fairly hardy...but if 1/3 of my stock die, I'm not so sure.

 

[nmonks]

Hello amcalab!

Saying that fish are "hardy" is a relative thing, and most fish that were hardy in their wild form are delicate in artificial varieties. So while wild-caught platies and guppies are indeed extremely robust and tolerant, the artificial forms (anything brightly coloured) will be far less hardy. This is because they are all inbred to create the bright colours and fancy fins many people find attractive.

Anyway, first thing is to understand what kind of water your fish need. Platies prefer hard, alkaline water. You want a hardness above 10 degrees GH, and ideally as hard as you can make it. If you live in a soft water area, it's well worth adding some coral sand to the substrate. This will slowly dissolve, raising the hardness. Secondly, your pH should be around 7.5 rather than 7.0. Again, coral sand will help here.

The next thing is about salt... and I keep saying this again and again: aquarium tonic salt is a con and you don't need it for freshwater fish! Platies do not live in brackish water. In the wild, they rarely, if ever, swim into water where there is salt. So do not add salt to the aquarium. Use it in the kitchen or to de-ice the sidewalk but don't use it in a freshwater aquarium. I have no idea what a "half dose" is -- but if anything, anyone, anywhere gives you a dosage in "teaspoons per gallon" or something similar: be skeptical of such help! The only proper way to use salt is by measuring specific gravity (e.g., 1.003).

Fish clamp their fins for different reasons. Tetras clamp their fins normally because they use their tail for swimming and the pectoral fins only for adjusting their position. Cichlids, on the other hand, use their pectoral fins for swimming slowly, almost like paddles. If cichlids clamp their fins, they are sick or stressed. Same with platies and other livebearers. So well done on spotting this.

Adding twelve fish all at once to a newly cycled tank wasn't perhaps the best thing to do, but assuming that nitrites and ammonium are zero, obviously no harm has been done. I'd be checking that the oxygen is at a decent level: is there plenty of water movement? Bubbles aren't important, but there MUST be a strong circulation of water around the tank, especially from the bottom to the top. It's this circulation that oxygenates the water, not bubbles or splashing. To check, put something at the bottom of the tank, like a piece of flake or a plant leaf, and see how it moves about. If it just sits there, that's bad. You want to see things move across the bottom of the tank switftly: that shows you have good circulation. When fish cannot get the oxygen they want, they get stressed, and will behave in exactly the way you describe. Eventually, they will get sick and die.

Cheers,

Neale