PLEASE HELP!!!

Question
Hi Karen... I have a 75 gallon established freshwater tank.  Things have been going very well up until a few weeks ago.  I have a community tank:  Angels, Tetras, Catfish, Painted Swords, Bosemani Rainbows, etc.  In the last two weeks I've had 4 Platys die, the last one I took in to have analyzed and they said he had bacteria in his gills.  I'm treating the tank with a mixture of Metranidazole and Kanamycin (sp?).  (Did treat with Furan before that but it did no good).  All my fish appear to be very stressed, breathing fast and hanging out at the top of the tank.  I have a Maxi Jet 1200 for water movement and a Marineland 360 canister filer.  I've been told there is plenty of oxygen in my tank.    

I guess I have many questions.  Can bacteria be brought in on freshwater plants and other decorations like petrified wood, rocks, etc? and can the bacteria live on these things?  Should I remove my plants when using meds, and get rid of everything in my tank??  Are these things contaminated?  Also, will the bad bacteria be caught in the canister filter trays?  Will it live in there??

As you can see, I'm desperate.  I just love my fish, especially my Angel's... can you give me some advice?  THANK YOU SO MUCH!!!!

Answer
Hi Jeanine,
Sorry to hear about your trouble... :(

While bacteria may have infected the one platy's gills. I'd wouldn't be very confident in saying that bacteria is responsible for all the fish loss and stress. Bacterial infections usually appear on fish as red blotches, streaks, open sores, or even internally as swellings visible outside of the fish's body. Bacterial infections are most often caused by an accumulation of filth in the aquarium, such as a buildup of waste and other debris in the gravel bed and filter. Similar to human environments and animal enclosures, when waste accumulates, bacteria will thrive as will other illnesses. While the water may be clear, the fish could easily be swimming in a soup of dissolved organics and wastes which weakens their immune system.

I didn't notice anywhere that you had your water tested. If you haven't, definitely test it right away with good quality liquid tests as these are much more accurate. The symptoms you described with breathing fast and gasping at the surface (despite adequate oxygenation otherwise) are something I've personally encountered to be associated with poor water conditions or even severe toxins like nitrites. I once had an issue with a once perfectly healthy established planted tank, one day the fish all started gasping and behaving very similar to what you described, having tested the water there was a sudden spike of nitrites. I'm still not 100% sure what caused this but when the fish were rescued and moved to a healthy tank they recovered within 5 minutes. Meanwhile I cleaned the tank and found tons of "clogged" pockets of gravel in the shallow gravel bed. Clogged pockets can form easily under rocks and driftwood where its hard to vacuum and can be a continuous source of excess pollutants constantly leaching into the water.

So what I would do an emergency 30-50% water change and gravel vacuum very thoroughly. I'd repeat these daily water changes until you are sure all is well. Try to test your ammonia, nitrites, and nitrates as well. Test your pH too to make sure there isn't any unusual drop in its level.

Be careful because when using medications in any tank, it can wipe out your beneficial bacteria and cause ammonia and nitrite spikes. This is a double whammy on the fish, any sicknesses they might have, plus medication stress, plus poor water quality. Make sure to try to pay extra attention to doing frequent water changes and tests to make sure all is well.

Bad bacteria can really only be brought in on plants if that plant was growing in a tank with fish swimming about in it at the place you got it.And if those fish were infected. Things like petrified wood or rocks not really so unless it was submerged in a tank with infected fish. Most plants don't tolerate medications very well and I've heard you should throw out all live plants when treatment is over because they can "harbor" the disease all the time. I'm not sure whether this is really true or not. Its possible.

As for the canister filter. If you have a major outbreak of disease that wipes out all the fish then you should do an overhaul cleaning, rinse out the canister with hot water and salt and throw away all the filter media and get new. If your fish recover after an illness I don't think it'd hurt to leave the filter as is, medication would be circulating through the filter too and should be killing off bad bacteria living in the filter as well.


Honestly I probably wouldn't treat the tank with meds unless all your fish are showing visible signs of disease. The symptoms you described sound simply like reactions to poor water quality.

Best of luck and I hope this helps!
Karen~