Dying fish.

Question
Dear David,  I have recently returned to an old hobby by setting up a 20 gallon tank.  It has been running for 3 months and things have been fine until 10 days ago when I bought an angel and tetra from a different store.  The angel died the next day and when I returned it I saw the tank it came from marked Not For Sale.  I have since lost 5 fish. The store gave me BiFuran which I started 3 days ago but this AM the tetra I bought 10 days ago also died.  Besides turning the water a glow in the dark green and having to do daily water changes while I treat, do you think I am out of the woods or should I be looking at something else? I have 2 dwarf gouramis, 4 neons, 4 zebras, a cat, 5 angels and a partridge in a pear tree.  Ok, maybe not the partridge. What a terrible feeling to be watching this happen. Any advice would be very appreciated! Martha

Answer
Hi Martha:  Welcome back to the hobbie.  When new fish travel from the aquarium  to your house they go through a great deal of stress.  Stress is one of the leading causes of disease and death in fish.  Angelfish are one species that do not tolerate stress very well.  They are very slow and methodical fish and get distressed anytime their environment changes.  That is probably what started this whole mess.  The good news is that if the other fish in the tank are not sick then I doubt they will get sick.  The same scenario for the new tetra is likely as well.  I work in an aquarium and I have watched as clerks try to catch fish... sometimes they chase them around the tank with the net too long or too much for the fish to even survive very long afterwards.  Another issue to be concerned with is the differences in pH between their tanks and yours.  Always insist that they test their pH for you and feel free to take them a sample of water from your tank.  I have had tanks that for whatever reason had a pH of 6.0 when my tap water is 7.6... no explanation of why but the point I am making is that our tank pH changes without reason sometimes and fish will die if the difference between tank pH is too great.  I can not stress enough to fish buyers that new fish must be quarantined for at least a week.  Let me adjust to a small tank where there are no dangers for enough time that they can recover from the shock of their journey.  It is also a lot easier and less expensive to treat a small tank then a larger one.  I hope this helps and please ask away if you have other questions.  dave