Tropical Fish Diseases

Question
I have a Jewel Trigon 190 which has about 30 fish in of various sizes, nothing too large.  The tank is very well established with a large selection of plants, fine gravel, rocks & bogwood.  The tank runs at a constant 28 Degrees C, has a mature filter & air pump.  All water entering the tank is treated with conditioner & water quality is checked on a weekly basis.  since I've had the tank there have been bouts of fish dying in small numbers for no apparent reason,  No physical signs of disease or abnormal lesions etc on any fish.  This usually occurs when I add new fish to the tank, however not necessarily the new fish are affected.  I have treated the fish with Melafix, Pemafix, Bactozyme & other treatments as directed but still the fish go on dying.  Please help as I am now lothe to add anything else to the tank in fear of losing it.  Would be grateful for your suggestions.  Many thanks  Jez.

Answer
Hi Jez,
It is a high possibility your new fish must be introducing diseases into the aquarium at one time or another. If all water parameters are normal (ammonia, nitrite at zero-- nitrate at least below 40ppm) then this rules out water quality issues. Please Don't add anymore medication to the aquarium--many meds can distrubt the biological filter causing a re-cycling in some cases. It is very common to get a bad batch of fish from the petstore. I have had this problem many times and it is well known problem. The first steps in insuring a healthy fish batch is to check all the occupants in the dealer's tank. All should be healthy and not stressed. Your second move would be to quarantine the new arrivals for at least 1-2 weeks in a seperate smaller aquarium, outfitted with a sponge filter or power filter. Along with a heater, thermometer, and top cover. A quaratine tank can be as small as the basic 10 gallon aquarium. Run all the essentials of a basic aquarium on it, just keep it simpler. Quaratining will save your current fish from a disease. There are too many instances of beautiful aquariums being wiped out from a disease introduced by new arrivals. I would never want yours to be one of those.

Bad batches of fish can be hard to avoid, you won't get them everytime. But you must look out for warning signs, excessive ill or gasping fish in most of the dealer's tanks is a big problem. All the fish should be healthy--oftentimes it is impossible to keep from having a deceased  fish in one or two tanks but avoid those where it is excessive. ~*Aclimate your new arrivals to their new aquarium slowly, floating their bag for about 20 minutes and then later adding half a coupleful of aquarium water into the bag every 5 minutes or so. Do this until the bag is filled (tip: it's much better to do this in a clean container, like a unusued 1 gal pitcher) just pour in half cupfuls until your bag or container is filled. Then you can consider your fish are acclimated and net them gently into the aquarium or quarantine tank.
*Quaratining any more new arrivals is your best bet at this time. Always make sure there is no ammonia in your aquarium water--nor nitrite. Any chemicals, cleaners, airsprays, and even perfume should not be used very near the aquarium. I'm trying to eliminate all possible causes of losing your fish.

Losing fish for no apparent reason requires some detective work. Insuring your new arrivals are quarantined and watched very closely for any signs of disease is essential. As is making sure your water quality is excellent and clean, and your fish can live in your current water parameter levels.

I really hope this helps! If you have anymore questions, feel free to email me...

I wish you the best!!
Happy fishkeeping!
Karen~