i have recently bought two new goldfish common and put them into a ten gallon tank with fish the size of neon tetras called shark minnows they have already killed one of my goldfish by giving it fin rot i dont have another tank but for some reason they leave the other goldfish alone?? But now he had these brown streaks on his tail but thier gone!!! And they keep coming back hhhhhheeeeeeellllppppppppp mmmmeeeeeee

just so koko doesn't have to

<font color="red">Test Results for the Following:
Ammonia Level?
Nitrite Level?
Nitrate level?
Ph Level, (If possible,KH and GH and chloramines)?
Ph Level out of the Tap?
Tank size (How many Gals) and How long has it been running?
What is the name and size of the filter/s?
How often do you change the water and how much?
How many fish in the tank and their size?
What kind of water additives or conditioners?
Any medications added to the tank?
Add any new fish to the tank?
What do you feed your fish?
Any unusual findings on the fish such as "grains of salt",
bloody streaks, frayed fins or fungus?
Any unusual behavior like staying
at the bottom, not eating, ect..? </font>

it'd really help everyone out if you'd answer those questions. i don't know much about disease but the people who do will need something to go on!

Hi there black tail As pickles mentioned, please answer as many questions as possible but just off the top it sounds like they're exposed to high levels of ammonia. This is the brown markings you see. If it happens once, this is ok but to continue happening means you've got some issues in your tank.

Secondly, I wouldn't put commons and shark minnows together. If I'm not mistaken, the shark minnows (schooling fish) are territorial and omnivores and will eat smaller fish etc. (someone correct me if i'm wrong) and there's too many fish in your tank so this would also contribute to your problems.

So for now, if you could answer as many of the questions as possible and someone with more knowlege on shark minnows will hopefully come along to enlighten us a bit more

Ive already in another thread told you that you have bala sharks which are tropical and grow to 14 inches.

Please dont start another thread and answer the questions above.

In a 10 gallon tank you are overcrowded if indeed they are bala sharks so best to take them back.

I thought they were balasharks. Not a good mix and dangerous in a 10 gallon

How are the fish doing?