Large Black Patch On Fish Nose Appeared Almost Overnight

[Guest fish questions]

I have two goldfish in a coldwater tank and recently one has (very quickly) developed a large black patch on its nose. It started quite small as a fluffy looking fungus but almost overnight has gone very dark and looks quite nasty.

Some pictures here:

http://img181.imageshack.us/img181/7093/lpic6250.jpg

http://img143.imageshack.us/img143/5143/lpic6252.jpg

[*]Tank size (how many gals.) and how long has it been running? about 8 litres, been running 1 year.

[*]What is the name and size of the filter(s)? no filter

[*]How often do you change the water and how much? every 4/5 days full water change, water always treated.

[*]How many fish in the tank and their size? 2 goldfish, average size (3-4 inches)

[*]What kind of water additives or conditioners? king british tap water safe.

[*]What do you feed your fish and how often? daily in the morning. tetra flakes.

[*]Any new fish added to the tank? no

[*]Any medications added to the tank? no

[dogsbykat]

Welcome Sorry to hear you're having fish trouble. Your problems will be related to water quality, as your fish need 20 gallons of space each, so your tank is just way too small. Do you have a larger plastic tote you can move them to? What are you using for filter and bubbles?

[Captain Findus Goldfish]

I am welcome!

I agree with Buggy.

You need about 60-70liters per goldfish (even a bit more as you have single tails which grow very large). And they NEED filtration. 10x turnover per hr. So for a 150liter tank, 1500liters per hour.

Once you fix the water problems, the fish problems will resolve themselves most likely.

You can read about the Nitrogen Cycle following the link in my sig

[Lupin]

Looks like a scrape to me. Any abrasive decors you have? Even if it is, the poor water quality would still contribute to the presence of infection.

I echo what others said. A tank upgrade is really needed. If a large tank is not an option at the moment, a large rubbermaid tub or fiberglass tub will do them favors better. A 10x filtration is also a must for them as Federica correctly advised. Please do get API liquid test kit as you study the nitrogen cycle indicated in Federica's signature.

Water changes are a must at this point! I'd do daily water changes until you can upgrade.

And for future reference, I'd suggest switching the foods. No flakes please! These ones are not as nutritious since they cannot hold the vitamins firmly enough. The vitamins just degrade quickly when exposed quickly to air and light. I'd suggest switching to fresh foods such as frozen bloodworms, chopped shrimps and daphnia, vegetables, homemade gel foods and sinking pellets. Hikari Lionhead or Saki Hikari will do.

Hope this helps.

[Guest fish questions]

thanks so much everyone, ill change the water now and look for a better tank and alternative food in the morning.

i should correct my first post... its a 15 litre tank, but still too small i guess. thanks again!

Edited October 17, 2010 by fish questions