15 Gallon Tank Urgent help! White fungus, columnaris?


Hey guys! I have a 15 gallon community tank running fully cycled and stocked about 2 weeks.
Last week I lost 3 guppies but soon learned my water may be too soft for them so that kind of put my mind at ease...

I was away from home the past 2 days. Made sure to do a 50% water change and feed before I left to tie things over.

Came home today to a dead rasbora floating at the surface (that makes 4 of my school of 6 now dead in space of a week ) AND to add to this my honey gourami now has a white fungal build up on his mouth, won't eat and stays at the bottom.

I checked again before bed and found my other gourami who was fine earlier is now rocking back and forth weirdly at the bottom of the tank so I feel he is next for whatever my tank is suffering from...

Any ideas what could be causing this? I'm hoping not columnaris!

My parameters seem fine.

0 ammonia
0 nitrite
10 nitrate
pH: 7.2
Temp: 79°F

2 honey gourami (illness symptoms)
6 cory cats (all ok)
3 guppies (started with 5)
2 harlequin rasboras (started with 6)

From my reading on the matter, I've decided to order Waterlife-Myxazin to treat this issue. I feel it could maybe be all down to a disease one of my fish brought into the tank last week. I don't have a backup tank to quarantine fish so fearing the worst now with the rest of my stock still in there.

Any help appreciated!


  • Thread Starter



What is the water volume of the tank?
54L ( 14/15 gallons)
How long has the tank been running?
2 months
Does it have a filter?
Eheim pickup 60
Does it have a heater?
Marina 100w
What is the water temperature?
What is the entire stocking of this tank?
6x cory catfish
5x guppies (2 dead)
2x honey gourami (1 dead)
6x harlequin rasboras (4 dead)

How often do you change the water?
Every 5 days
How much of the water do you change?
What do you use to treat your water?
Prime and also flourish for my plants
Do you vacuum the substrate or just the water?

*Parameters - Very Important
Did you cycle your tank before adding fish?
Yes for 2 months using dr Tim's ammonia solution
What do you use to test the water?
Api master test kit
What are your parameters? We need to know the exact numbers, not just “fine” or “safe”.

Ammonia: 0
Nitrite: 0
Nitrate: 10
pH: 7.2

How often do you feed your fish?
Once a day
How much do you feed your fish?
A few flakes on top. About 6 to 8 sinking pellets for cory catfish. Also feed fluval bug bites every now and then.
What brand of food do you feed your fish?
Fluval vegetable flakes and king British sinking pellets, king British bloodworms
Do you feed frozen or freeze-dried foods?
Sometimes I give them bloodworms

Illness & Symptoms
How long have you had this fish?
2 weeks
How long ago did you first notice these symptoms?
5 days
In a few words, can you explain the symptoms?
Lost 3 guppies, 4 rasboras and 1 gourami. The guppies all died suddenly (overnight), the rasboras seemed to have lost colour and would be dead soon after.
Have you started any treatment for the illness?
I have ordered myzaxin to treat the tank for disease.
Was your fish physically ill or injured upon purchase? Not noticeably
How has its behavior and appearance changed, if at all?
My gourami that died last night had white fungus on the mouth area. Wasn't eating or swimming as usual. Just floating around and very distant.

Explain your emergency situation in detail. (Please give a clear explanation of what is going on, include details from the beginning of the illness leading up to now)

I've lost 3 guppies, 4 rasboras and 2 gourami in the past 2 weeks. It's difficult to say who might have had some illness which has spread in my tank. I first added 3 cory cats, 5 guppies and 2 gourami. 2 guppies died about 3 days later (possibly due to soft water in my house).
I went to my fish shop again and then purchased 3 more Cory's to make a school of 6 and 6 rasboras.

Within another week I had lost 4 rasboras, they'd discolour and soon after die. Last night I lost the last fish to date, my honey gourami who had symptoms of mouth fungus. So all I've left now is 1 gourami (showing symptoms of stress), 6 cory cats (seemingly fine haven't lost any to date), 3 guppies.

Any help appreciated!


Is it really fuzzyb/ cotonlike?

It's a Thicklipped gourami btw
  • Thread Starter


DoubleDutch said:
Is it really fuzzyb/ cotonlike?

It's a Thicklipped gourami btw
He has since passed on unfortunately. He wasn't well at all last night and I found him dead this morning on the substrate. :(

I took photos yesterday and you can see the white fungus on his mouth area



Mmm sorry to hear
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