Platy with split dorsal fin

[jlinsey]

We have a 6 gallon tank with a platy a tetra and 8 baby mollies (in an enclosure). It has been set up for about a month and is not yet cycled, but we are keeping the water quality OK with daily 35% water changes. I have been watching the fish closely, as we lost our first two, and over the past week or so, the platy's dorsal fin looked a bit ragged if you looked very closely. Today it has a big split, about 75% of the way down the fin to the body. It is located about 1/3 of the way from the front of the fin. Otherwise, the fish looks fine. TIA for any advice you can offer!

 

[Zagz]

Is there anything sharp in the tank? With those tankmates it seems very unlikely that it is any form of aggression. I would suspect something the platy brushed up against. Is there any white or reddish areas on the fin?

 

[Devilishturtles]

Keep doing your daily water changes, and add some melafix to your tank. The reason for the fin damage is likely poor water quality. Do you have a test kit that you can test your water with? If so, can you post the readings here?

 

[jlinsey]

All that is in the tank is the filter, heater, thermometer, one lava rock with a hole in the middle, one plastic plant and the plastic frame with mesh around it for the baby mollies. The fin does not have any white areas...reddish it's hard to say because the fin is bright orangy in color but I would say it looks normal except for the split.
The tetra does like to chase the platy around and they go pretty fast for the size of the space they're in so I guess it could have been an injury.
I tested this morning:
ammonia 0-.25
nitrite 1.0
nitrate 10
hardness 75
alkalinity 0
ph 7.2
I have been testing the ammonia daily, and it's been stable at .25 or less for 10 days. When we first tested after getting advice on AA, it was up to 0.5-3 though. I've been doing the strip for the other 5 parameters once a week, and this was the first time nitrite or nitrate was >0.
I read a bit of description of melafix. It sounds like it can help to heal the fin up so I'll try it. Thanks

 

[rich311k]

Do a water change you want that nitrite level down around .25 at least less than .5. You are in the second stage of your cycle, it is moving along. I would up your water changes to 50%.

 

[jlinsey]

Thanks for the advice!
I have added the melafix proportionally with the last two water changes and the fin is looking better already! I did not take the charcoal out. Lastnight we did a 50% PWC and this morning the nitrite was down to 0.5. Will do a 50% PWC again tonight.
Since I am doing such frequent water changes, should I keep adding the melafix proportionally each time for the 7-day period? I don't want to over do it.

 

[rich311k]

Yes add to replace the percentage you removed.

 

[jlinsey]

Just finished with the 7 days of melafix. The dorsal fin is just about good as new and all of the platy's other fins look better than ever 8)
Thanks everybody!

 

[rich311k]

Good to hear.