Can you tell me anything about the fungus in my fish tank?

Question

It would appear that I have grown a cotton-like fungus in my fish tank. It started to appear on one of our tank decorations and we removed it. Shortly thereafter my two angel fish died one after the other. I had a pleco that survived an extra couple of days after the angel fish died. My pleco died the other day and was entirely coated with this substance when we found him.
I guess what I'm really asking for is a scientific name for this and what I can do to prevent it next time.

I should add that you can not over feed fish in the first week. My tank was only set up for a week.

Answer 1

What you have would be either Saprolegnia or Achlya. These are very similar and would need to be differentiated microscopically. You can find them in most aquarium books lump together as fish "fungus", although they aren't classified as a fungus by biologists anymore.

You'll have trouble preventing it - it's in most every water supply, so it'll come in every time you do a water change. It can be knocked back with a medication, but it's not likely that it would be the primary cause of your fishes' deaths - it's usually secondary to another problem.

Were your fish showing any external injuries? Both "fungi" will infect open sores if they had a wound or bacterial infection.

Do you have a water test kit? Do you know what your ammonia, nitrite, and nitrate were at the time of the first fish's death? After the first death, the ammonia would certainly rise, especially if the death wasn't noticed and the fish was in the tank for a while. And this may have been the cause of death, at least for the last two fish, if a water change wasn't done after removing the dead fish. A good growth of either "fungus" takes about two days.

I'll give you some links below so you can read more about these "fungi":

Answer 2

often the cotton like substance that you find under your decorations is extra food that the fish didn't eat. Which can cause your fish to die when your tank is not clean properly. Most fungus would be found on the fish itself. I would recommd a 1/3-1/2 water change on your tank using a vacuumed sphyon make sure you clean the rock really well and get all that junk up. Also check your waters ph, ammonia, nitrite and nitrate and make sure is normal before you consider adding new fish

it might not be "over feeding" it just be excess food. It happens all the time with ANY fish tanks life.

It does help to know that the tank is only a week old. you want to make sure that your deco didn't have anything on it before you put them in the tank, that happens alot to

Answer 3

There is a cottony fungus called "velvet", that can attach itself to most anything in an aquarium. When it attaches itself to fish, they will die if not treated. Get some "pimafix" from your petstore. Good stuff! And since there was already evidence of it growing before, it necessary to treat any other fish, do a 20% water change to slow the growth. Also, be sure to remove any decorations, large rocks, fake plants, etc, and soak them in diluted bleach/water, in the sink or a bucket for 20 or 30 minutes. It's also a good idea to take a clean wash clothe and just go over the insides of the class. Velvet clings to EVERTHING. It's only after it is visable, that it has already produced eggs and multiplied. Also, monitor the water temperature, fluxuating temps. can cause fish to be stressed and more suseptible to disease,

Answer 4

Fungus like this grows on excess food and rotting flesh or plants in the tank. The fish probably died because of a build up of ammonia from their own waste and rotting food.
You can over feed in any length of time. If you have any food left in the tank after the fish have fed you are over feeding.
If I had set up a tank for only one week there would be no fish in yet as the water had not gone through the nitrification cycle.
The water still does not have the number of bacteria capable of consuming the waste ammonia from the fish.
How to set up a tank and cycle it correctly is available on my web site for free.
http://www.artsaquaticsandanimals.co.uk

Answer 5

Hello,

From my opinion that is Saprolegnia sp., a type of fungus that looks like white cottony tuft. It usually present in established fish tank in low numbers and become opportunistic when the aquarium hygiene declines. eg. from excess uneaten decaying foods, infrequent water change, etc.

I don't think Saprolegnia infection will kill your fish in 1 or 2 days. Maybe it's ammonia that killed them. (New Tank Syndrome)

Saprolegnia can be treated with Methylene blue or aquarium salt, adjust dosage accordingly to your tank size.

To prevent: maintain regular partial water change and cycle well your new tank.

Hope that helps.

Answer 6

it's gross.