New Member
Aug 28, 2018
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Hi, im new to this site and desperately need help with one of my fish. Ive had a 10 gallon for a couple of months and one of my most recent additions is a pair of dalmatian mollies. One of them was rather small but thats likely just because hes young. I noticed the smaller of the pair resting on the bottom of the tank, but going up for food relatively easily. I bought some peas after work in hopes that he may just be feeling sick from constipation or something of the sort. I have him floating within the tank in a betta cup so he can rest and go up for food easily. My tank is freshwater but after some research last night i bought some aquarium salt in hopes that he would respond well. I added it a few hours ago (a very small amount in the cup), but he seems to be getting worse! His eyes are swollen and seem a little white on the eyelids (I cant tell if its his color or if its something different). He has begun to flop around on his sides and is floating generally facing up vertically. Im assuming its a swim bladder problem but im finding lots of conflicting information. Im hoping i can get some help!


Fish Guru
Jan 26, 2008
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Perth, WA
Hi and welcome to the forum :)

The biggest issue with mollies and other livebearers is poor water quality (ammonia nitrite or pH) and soft water.
Mollies need water with a general hardness (GH) above 250ppm and a pH above 7.0. If the pH is below 7.0 they will have issues and if the GH is below 250ppm they have issues. If there is any ammonia or nitrite in the water it will kill them pretty quickly.

If you don't have test kits, you can take a glass full of tank water to the local pet shop and ask them to test the water for you. Write the results down when they test it and post them here. The results will be something like this: Ammonia 0.25; Nitrite 0.5; Nitrate 25ppm; pH 6.8 and GH 150ppm.

The best thing to do if any fish is looking unwell or not happy, is 75% water change and gravel clean the substrate each day until the issue is diagnosed and resolved. The big water change will dilute nutrients and disease organisms and help a lot.
Make sure any new water is free of chlorine/ chloramine before it is added to the tank.

If you want to add salt to the tank, you add 1 heaped tablespoon of rock salt (aquarium salt), sea salt or swimming pool salt per 20 litres of water. If you only have livebearers (mollies, swordtails, guppies & platies) in the tank you can double that dose.

To work out the volume of water in the tank:
measure length x width x height in cm.
divide by 1000.
= volume in litres.

When you measure the height, measure from the top of the substrate to the top of the water level.

There is a calculator/ converter in the "How To Tips" at the top of this page that will let you convert litres to gallons if you need it.

If you can post a picture of the sick fish it will give us more information on what is wrong with it :)


Supporting Member
Tank of the Month!
Feb 25, 2009
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In addition to Colin's advice, I must mention that a 10 gallon tank is much too small for mollies as they grow. So should this one not survive (and if the fish is unable to remain upright it is not likely to survive, just so you know; swim bladder issues are impossible to rectify) please do not acquire another molly.

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