Mollie diseased? ASAP

Question
QUESTION: Hi,
I have this mollie and i noticed today that its tail has a sort of furry white mouldy looking thing around its tail. I put him in a separate tank. My dad seems to think that putting salt in the water helps heal them so i did that. What is wrong with it and what can i do to fix it.

I have around 15 fish but i have no clue how large the tanki it. It is a good size though. We changed the water 4 days ago.
I would appreciate any help you could give ASAP.

Thanks
Sam

ANSWER: Hi Samantha;

It could be a bacterial or fungal infection. You will need to treat with a medication from your local fish store. Look at the packages of medicine and choose once that treats what your fish has. Salt is a good thing to add for your sick molly too. Change part of the water in the sick fish's tank daily too. Fresh water helps boost the immune system and aids in healing. Your fish may have been injured or irritated and then became infected.

It's really important to keep the water very clean for the health of all your fish. Change 25% of the water at least every week and vacuum the gravel too. Let me know the dimensions of your tank (in cm or inches) and I can tell you what the gallon capacity it is and how many fish are safe in there. Also let me know what kinds of fish, how big they are and how long your tank has been set up. I can help you keep all your fish healthy once I know more details and hopefully keep your other fish from getting sick too. I hope your molly feels better soon...

At Your Service;
Chris Robbins

---------- FOLLOW-UP ----------

QUESTION: Hi Chris,
Thank-you for your help. I will change half of the mollies water today.

I measured the tank but im not sure how accurate it was as i could only find 15cm rulers to use! It was around 58cm long, 29cm wide, and 34cm heigh.

Here is a list of the fish I own & approximately how large they are.(This is in the large tank i took the sick mollie out of.

1 guppy (2.5cm)
1 dwarf gourami (6cm)
1 mollie (5cm) [not the sick one]
6 swordtails ( between 4cm-7cm)
1 neon tetra (2.5cm)
2 sucker catfish (6.5cm) [i think they are sucker catfish but i am not 100%]

The sick mollie is around 5.5cm long.

The tank has been set up since april so around 5months

Thanks for your help!
Sam  

Answer
Hi Sam;

The water changes for the sick one will definitely help. I hope he feels better soon. Your main tank is going to need some water changes too so that the other fish don't get sick. It's pretty crowded in there so with cleaner water you will notice that they have better color and more vitality as you go along. I would make 25% water changes twice a week for awhile to get their immune systems boosted. Vacuum the gravel once a week too. It's amazing how much solid waste can accumulate there.

Your tank holds about 57 liters of water. The maximum safe population for a tank that size is about 30 cm. You have quite a few more than that and some of those guys aren't actually full grown yet. It would be good to get either a second tank of at least 57 liters or get a second one about the same size. I don't know what size your isolation tank is but you might want to move some over there (once the molly heals) if it's big enough. Here is a web page with a calculator that tells what the capacity of a tank is based on it's dimensions;

http://www.aquariumcity.net/Enter_your_Dimensions.htm

Good luck and I hope all goes well!

At Your Service;
Chris Robbins