Medicine and the carbon filter?

Question

I was treating my goldfish with a medicine for fin rot and fungus, but its been 5 days with daily treatments and I see no change, if anything its much worse. I have a 200 ltr tank and tonight I put 45 ltrs of fresh water in and put the carbon filter back. I want to try a new medicine I picked up today. My question is, how long will the carbon filter take to remove the old medicine so I can use the new one safely?. Thanks:)

Answer 1

Carbon removes medication on contact, so as long as it takes for the filter to cycle through the tank is how long the medication will be in the water.  If the filter moves 50 gallons per hour and it's a 10 gallon tank, after about 12 minutes, the medication should be gone... I'd wait an hour just to be safe, though.

Answer 2

I would suggest doing at least a 50-75% water change to help remove medications. The carbon should take at least a few days to absorb any left over medication. I would wait at least a few days, then you can probably re medicate, but remember to remove the carbon again.

Answer 3

Quite possibly it never will.  It will depend on the ingredients of the medication.  Some like copper are readily removed by carbon, but not all medications are.  A good indication would be if the instructions of the former medication tell you to remove carbon when treating - if it doesn't specify to do this, carbon may not have any effect, and you'll need to do a series of large water changes to reduce the amount present.

Also, be certain that what you goldfish has is fungus/fin rot.  There's a bacterial infection (Columnaris) which looks similar, but can be differentiated by looking closely at the appearance - fungus (Saprolegnia and Achlya) have long, straight filaments and an irregular outline - this rarely attacks a healthy fish because their immune system is capable of fighting it off.  If your fish has a fungal problem, it may be secondary to another problem such as ammonia or nitrite in the water or improper temperature.  Ammonia can also cause the tail to erode, but the splits tend to be from the oouter edge inward (like the tail was ripped) while fin rot tends to occur along the edge only, and rot the entire edge inward.  Unless the primary cause of stress to your fish is also addressed, the infection will keep returning.  Columnaris has shorter matted (tangled) filaments and the infection has an outline that's nearly circular.  This is fast-acting and can be transmitted to other fish.  There are some medications that will treat both.

ADDITION:  After looking at your photos, I don't see any signs of either fin rot or fungus on him.  Fin rot would resemble these:  http://o-fish.com/HamaPenyakit/images/fi...

http://www.fishdeals.com/fish_diseases/f...

And fungus (at least in later stages a few days old) would look like these:  http://www.uib.no/bot/kurs/BB220/Algae/F... , http://www.practicalfishkeeping.co.uk/pf...

Columnaris would look more like this (notice the circular outline):  http://www.fishjunkies.com/images/Column...

While your fish does have noticeable white spots on the fins, what stands out more is the red streaking - this is a sign of either ammonia poisoning (high ammonia levels in the tank due to a new tank or recent use of an antibiotic that's killed the bacteria the converts the toxic ammonia to nitrate) or septicemia, which is a bacterial blood infection.  You can find more on both conditions in the same link I posted earlier.  If your tank is fairly new (less than 2 months old) the problem may just be ammonia from insufficent water changes (either not often enough, or not a large enough volume of water is being removed to keep the ammonia levels from building up). Do you test the water for ammonia and know the level in your tank?  You should try to keep this below 0.5 ppm.  If the streaking has only appeared since you started treating your fish, and you've used an antibiotic as one of your treatments, the ammonia may be the result of the loss of the beneficial bacteria.  However if your tank has been established for a while, and you haven't added any new fish to increase the ammonia being produced, the problem may be septicemia.  In either case, a large water change would be in order.

A final (and less known) possibility is that your fish has been infected by Dermocystidium (and this would also fit with the red streaking, particularly if this is what you're seeing as being "lumpy").  Rather than being eggs, these are spores.  There's no known treatment for this, but unless the gills are infected, it's typically not fatal.  I would suggest separating your fish if you believe this is a possibility as the spores that are released are capable of infecting other fish.  Again, I would recommend a large water change, and good vacuuming of the gravel to reduce the number of any free spores that are present in your tank.  Some additional info on this condition (there are several species of Dermocystidium, but the species affecting koi and possibly goldfish is the one with most available info):  http://www.fishdoc.net/disease/dermocyst...

http://www.fishbase.org/Diseases/Disease...