Unidentified fish disease!!!

[rebeccakatie1131]

hi everyone!! I need advice asap for my fish please as i dont have fish illness experience and they mean the world to me. I had 10 molly fish they are 1yr and 2months old (they were born in my tank) and last week they started to act strange... not interested in food as much just barely nibbling, hiding out in small groups in the bottom of the tank and just acting very skittish and not like themselves. We lost 2 mollies in one week.... i dont have any water testing kits (waiting for one to arrive in post currently) but took a sample of my water to local pet shop and they confirmed my water was good quality and suggested to add some aquarium salt for the mollies (which i purchased and have added a couple of times) So now this week, last night got home and one of my babies was struggling to swim he was showing severe signs of swimbladder (swimming vertically but actually flipping in circles slowly) at some points he was just lying on his back and it was pretty clear he was dying... there was another molly laying next to him in the corner of the tank... almost as family support it was heartbreaking. i tried to take him out to a seperate tank but he got extremely stressed and so did my other fish so i decided to leave him. This morning i checked them straight away and was shocked to see he was still alive struggling to breathe and just letting the current throw him around and even more shocked to see that the fish that had been supporting him was actually dead!!!!! The dead fish looked normal without any marks or injury or sign of disease (i had a look when i took him out of the tank) however the fish that was barely alive and struggling His tail had a white fluffy substance on it which was there last night a little bit greyish though, and today his tail was the half size of what it normally is so perhaps it could be rot fin? Around 4pm today this fish that was struggling died. I have 6 mollies in my tank and one common pleco named roger, i need advice to stop this disease from spreading which i believe it has already started, 3 of my molly fish have tiny white dots on them, just one dot in different places and i dont even know how to begin to research and treat this as alot of diseases are being suggested to me. I have attatched photos of the fish that died today (he is alive in these photos although he does not look it) and my fish with the small white spots on them if you look closely. Today i will do a 60% water change and change the substrate back to one they had before which is a natural aquarium soil (rogers favourite) . I really dont know what im supposed to do in a situation like this so please give as much advice as possible! Thanks

[Gingerlove05]

Hello and welcome
Sorry for your losses and sorry your having issues
Hopefully we can help, unfortunately the pics haven’t attached so its hard to say what it could be.
What is your water hardness? (Not the ph)
you can normally find this out on your water supplier website. Mollies need hard water although there are some species that need brackish or salt water. I wouldnt advise the salt as Roger wouldn’t appreciate it long term.
how big is the tank? And what filtration do you have? As common plecs can get pretty big and some species of molly can also grow quite big and need a good amount of room and they can all be a bit messy.
Also why did you change the substrate?
Sorry for all the questions just trying to get a bigger picture

[rebeccakatie1131]

Hello and welcome
Sorry for your losses and sorry your having issues
Hopefully we can help, unfortunately the pics haven’t attached so its hard to say what it could be.
What is your water hardness? (Not the ph)
you can normally find this out on your water supplier website. Mollies need hard water although there are some species that need brackish or salt water. I wouldnt advise the salt as Roger wouldn’t appreciate it long term.
how big is the tank? And what filtration do you have? As common plecs can get pretty big and some species of  molly can also grow quite big and need a good amount of room and they can all be a bit messy.
Also why did you change the substrate?
Sorry for all the questions just trying to get a bigger picture

[rebeccakatie1131]

Hello and welcome
Sorry for your losses and sorry your having issues
Hopefully we can help, unfortunately the pics haven’t attached so its hard to say what it could be.
What is your water hardness? (Not the ph)
you can normally find this out on your water supplier website. Mollies need hard water although there are some species that need brackish or salt water. I wouldnt advise the salt as Roger wouldn’t appreciate it long term.
how big is the tank? And what filtration do you have? As common plecs can get pretty big and some species of  molly can also grow quite big and need a good amount of room and they can all be a bit messy.
Also why did you change the substrate?
Sorry for all the questions just trying to get a bigger picture

[rebeccakatie1131]

[attachment=1946][attachment=1945][attachment=1944]

rebeccakatie1131 pid='14887' dateline='1536793002']

Hello and welcome
Sorry for your losses and sorry your having issues
Hopefully we can help, unfortunately the pics haven’t attached so its hard to say what it could be.
What is your water hardness? (Not the ph)
you can normally find this out on your water supplier website. Mollies need hard water although there are some species that need brackish or salt water. I wouldnt advise the salt as Roger wouldn’t appreciate it long term.
how big is the tank? And what filtration do you have? As common plecs can get pretty big and some species of  molly can also grow quite big and need a good amount of room and they can all be a bit messy.
Also why did you change the substrate?
Sorry for all the questions just trying to get a bigger picture

[plankton]

Sorry for your losses.
What water are you using and can you tell what the hardness of it is?
Bottled water isn't always reliable, and any good conditioner will remove the heavy metals and chlorination from the tapwater.
The white spot in the first pic looks like an internal parasite of some kind causing it.
I would treat with something like Waterlife's Myxazin and see how it reacts.

[rebeccakatie1131]

Sorry for your losses.
What water are you using and can you tell what the hardness of it is?
Bottled water isn't always reliable, and any good conditioner will remove the heavy metals and chlorination from the tapwater.
The white spot in the first pic looks like an internal parasite of some kind causing it.
I would treat with something like Waterlife's Myxazin and see how it reacts.

[rebeccakatie1131]

Sorry for your losses.
What water are you using and can you tell what the hardness of it is?
Bottled water isn't always reliable, and any good conditioner will remove the heavy metals and chlorination from the tapwater.
The white spot in the first pic looks like an internal parasite of some kind causing it.
I would treat with something like Waterlife's Myxazin and see how it reacts.

[plankton]

Fungus is usually a secondary problem following damage.
Melafix won't cure anything, but may help to contain the problem.

[Suelo]

Hello, & welcome to the forum.

Have you been using only bottled water in the tank? If so, I'm sorry to say, I wonder if that might be the problem.

Looking at the label of your water bottle, it is listing calcium as 10 ppm. In fishkeeping, we usually talking in terms of General or Germany degrees of hardness (dGH), and 10ppm calcium converts to approximately 0.56 dGH. Your fish really need hard water - something in excess of 10dGH at least. I understand that hardwater fish kept in soft water can be especially prone to fungus and fin rot and other osmotic problems, so I wonder if that is at least part of the problem here? It doesn't seem very good advice from the fish store 

Wait and see what others think, but I'm wondering whether your fish would benefit from being kept in your tap water instead, although the changeover would need to be very gradual. Do you have any other fish in the tank?