Just experienced my first goldfish death; should I be worried?

[Davala]

Recently a goldfish of mine has been having problems, which then led to death a few minutes ago upon writing this. Basically; it seemed to have developed some sort of flesh wound to one side with some sort of white 'flesh' protruding from the cut. While this was happening it would lay on the bottom at the same spot for a while, and looked slightly unbalanced whenever he moved. This cleared up after a few hours (the white flesh disappeared maybe five to ten hours later) and he was swimming and eating normally. Today however, (around three days after the wound appeared) I noticed that the wounded area began to look very dark/black, and sitting on the ground continued. The fish died in the next couple of hours found laying upside down on the substrate, with a slight loss of colour from orange to silver.

My question is: was the death due to the wound, and if so how could a wound like this occur (I have found no sharp edges on any ornaments, etc)?
Also, are the other fish at any direct risk?

I have four adult goldfish and one youth in a tank approximately 130l/30 gallons in volume. All the other fish seem alright, although I am having a slight problem controlling waste levels due to a slightly underpowered biological sponge filter. I also don't have the capabilities to conduct any ammonia or nitrate/ite tests.

Any help would be much appreciated.

 

[FishyMcBites55]

where did you get your goldfish? Often times they are sick when purchased as they are met for feeders also four adult goldfish in a 30 gallon wth only a sponge filter is asking for problems. Goldfish are ammonia machines and really need a pond and sometimes struggle in tanks. I would reccommend and upgrade to the filtration with an aquaclear 70 powerfilter alongside the sponge. I would also reccommend upgrading to somewhere around a 55 gallon to add some water volume to prevent toxins from reaching deadly levels as fast. May I also ask what the water parameters were at the time of death?

 

[Davala]

I honestly can't tell you the appropriate parameters because I don't have the equipment to do so, all I know is the temperature - 24 degrees C. My tanks are all second hand from family members, so this is why I do not have much specialist equipment, etc. and the fish were bought through certified aquatics centres over a year ago with little problems. I won't be getting any more goldfish, and I have been stalling in getting a new filter as I'm quite overwhelmed by the options available and am unsure about which would be the ideal filter.
Sorry I can't be too specific about the variables and such.

 

[dandries]

I would question the water quality because I have about the same amount of fish in a 60 gallon with two filters. And the only way I keep the nitrates down is to do water changes once a week.

My advice is get a canister filter. I like the Fluval 306 and it seems to be working very well. But I use two filters because goldfish are very dirty. Adorable but dirty.

Sent from my SCH-I605 using Aquarium Advice mobile app

 

[kirkland795]

Goldfish generally need around 20 gallons per fish due to high ammonia in their waste as noted. I use to keep three goldfish in a 60 gallon and with one HOB filter and it was still high maintenance to keep water parameters in line. Test strips you dip in the water are pretty inexpensive to test your water parameters. It's really hard to know whats going on if don't know whats in your water. Sorry to hear about your fish. I hope the others do better.