Weird floating fungus(??) and dying goldfish

[Jaime Richards]

I have a mini vertical (stackable grow ups) with a 20 gallon basin full of water.  Up until a few weeks ago, I had a very healthy group of about 10 goldfish that were thriving and growing rapidly.  My plants are all healthy and happy.

Then, I added two plecos to eat the overload of algae growth (increased sunlight) and added 20 more goldfish and 2 plecos to a new system where I'm growing grapevines.  Within a week, every fish in the new system was dead, and my goldfish in my healthy old system were beginning to die one by one.  Next to them, is a GROSS floating gelatinous masses (photo below).

I'm losing roughly a fish a day.  I have three guys left.  I don't want to hurt my plants by treating my water with a fungicide.

Has anyone seen this or have any ideas on how I can troubleshoot it?

Thank you so much!

Jaime

[Jaime Richards]

Goldfish food, once a day.  They were totally fine until I introduced the two plecos (who died right away).  It has to be an illness or fungus...not the food.

[Jonathan Kadish NYC AA Chair]

Have you ruled out any issues with water chemistry... what are your PH, ammonia and nitrites?

[Jon Parr]

Fungus is often the result, not the cause. Plecos are really tough fish, and I've never had any die except by jumping out. What's the water temp?  I'd suggest salting the water at 2 ppt, and see if that helps. Cool water temps may have done the plecos in, and sudden doubling of fish population (and potential disease) may have caused the goldfish stress. Also, Plecos are calm by day, but often tank bullies by night. Ad of course, goldfish die for no apparent reason quite often. Salt is the easiest first step (fyi, strawberries don't like salt)

Jaime Richards said:

Goldfish food, once a day.  They were totally fine until I introduced the two plecos (who died right away).  It has to be an illness or fungus...not the food.

[Jaime Richards]

Thanks Jon,

I'm happy to try salt.  Just to clarify, I only added to very small plecos (to my indoor setup), the other fish I added to my new tank.  The only thing the two batches had in common was the plecos.  That's it.  Everything happened right after that.  Nothing else changed.  What's 2ppt?  Sorry, I just can't translate that.  I've never salted water before either.  I have 20 gallons of water...do I just pour salt in?  Thanks for your help, and sorry for my stupidity.

Jaime

[Jaime Richards]

What about sea salt?  I have a lot of natural sea salts....

[Jon Parr]

Yes, 2 ppt is 2 parts per thousand, or .2%. 20 gallons of water needs 1/3 pound of salt (5ish oz) to get 2ppt. 1/3 pound is the same as 1/3 pint, or 2/3 cup. I'm not an expert here, but I'm currently treating bluegill at 5 ppt as per a Texas U paper I read, and it's working great. Sea salt or rock salt is good, OSH sells 50 lb bags for $5, called course rock salt. 

[BenHehle Beamz]

this is not a metallic container right?

[Jaime Richards]

Nope - not metal!  Thank you all for your help!  I think I might suck out all of the slime, replace some water, add a cup of sea salt in the bottom and let them hang for a few days.

[Joel G]

If you add salt, your plants would also be affected. 

Just wanted to point out that in aquarium fishkeeping, it is a standard practice to quarantine new fishes for at least 3 weeks before introducing to the community tank.

[Vlad Jovanovic]

People salt at a rate of 1-3ppt, and have done so at times for years with no apparent ill effects to their plants. Except for some reports of strawberries not being very salt tolerable....

But Jamie, you still haven't given us your water quality parameters? Ammonia/Nitrite/pH etc...

With an "overload of algae growth" it would stand to reason that you may be experiencing ammonia spikes as some of the algae dies off (also less O2 as it blooms), and if there is for some reason a lot of extra sunlight hitting your tanks, your microbes would be slow to convert this ammonia to nitrite/nitrate. 

So listing your water quality parameters would help...what does your test kit say?

[TCLynx]

very many fish going into a brand new small system all at once, doesn't shock me that you might have deaths since a new system if not cycled up yet and you add the whole fish load, you can have the ammonia spike new tank syndrome and kill fish.

The older system, all those things the others mention can cause issues.  Perhaps the new fish brought in an illness or perhaps they just raised the load beyond what your current filtration and aeration could support.

Please note, plecos eat surface algae (which isn't actually a big problem) if your water is green though, the plecos won't help much and the added fish load overnight when the algae is also consuming oxygen might have left fish deprived of oxygen overnight and can cause deaths.  Shade green water from the sun and make sure you have plenty of extra aeration.  Dieing algae can also increase the load on the filtration as others have said and any increased load on the filtration uses up extra oxygen too.

The tank seems kinda small, has the weather gotten more extreme?  Large temperature swings from day to night and small tanks can be really hard on fish.  I almost killed the bluegill and catfish in my market system last month when we had a warm afternoon (water was 65 F) swing to a very cold night (water fell to below 40 F)  In the morning all my bluegill were sideways and a few of the catfish were lying around too.  The Goldfish and koi seems to fair the best with that swing but I was really worried the bluegill were dead.  They did recover and I made sure the temp couldn't swing quite so far again on them but that was a 200 gallon fish tank with another almost 200 gallons of sump tank.  A 10 degree F swing on the water temperature between day and night doesn't seem to bother my fish in the tanks at home but if the water temperature is swinging much more than that I think I'd worry.

Salting is a good fix for many illnesses and even just a general fish tonic to help slime coat and mitigate nitrite toxicity during a spike but you want to be careful to measure the amount you use and I generally recommend to dissolve it before adding to a fish tank because if you have the grains of salt sitting in the tank and a fish rests against it, it can burn them.

A bucket of salt under the water return into the tank can allow the salt to dissolve slowly and the water will overflow from the bucket into the tank if your set up allows for that.  Otherwise I just dissolve the salt in a container of system water and add it back into the system.