tank issues

Question
Hello again Ron.... I asked another expert this question but was unable to get an answer... I have posted the original question and the follow up question... do your best.

dave


I have been keeping fish for about two years and about two months ago I bought a small 7 gallon tall tank... its about one foot wide by 18 inches to two feet tall.  I bought this tank to house my six male guppies.  I have a ten gallon filter and an air pump/air stone for the tank.  I have not put a heater in the tank because the light on top warms the water quite well.  The fish died off in groups of three... smallest first... ok... I moved the remaining guppy to another tank, let the tank cycle for two weeks, ( cycle I mean... I treated the fish tank as though there were still fish in it... changed 25% water each week, added small amount of food, gravel vacuumed, etc) After two weeks I added a small algae eater and he lived quite well... I also added four live plants when I added the algae eater... three days ago I put in two tiny African cichlids.  One was about an inch and the other about 1.5 inches...both were siblings and healthy.... They are both dead.  I have moved the algae eater to the guppy fry tank.  The tank water (ill have it tested today) is clear, the tank is clean, there are no food build ups, the tank has plenty of oxygen, and good filtration (bio wheel), and the temp is almost always around 75 degrees, plus or minus a degree... lights off at night. Besides the algae eater... nothing else has survived this tank.... I have even added "dirty" water from the sponge filter in the guppy fry tank...  Any suggestions about how to make this tank safe for fish or should I just use it to grow plants?

---------- FOLLOW-UP ----------

QUESTION: well hmmm .. I use the same water in all of my other eight tanks with no casualties... I also treat each tank the same so if water was the answer fish would die in all other tanks.... This tank was cycled for two weeks before I added fish...so even though I use tap water and a dechlorinator there should be no chlorine left by the time the fish were added.  I did take water from the tank to the aquarium and they tested it for me... The levels were all good... though they didn't tell me what the values where.  The filter was moved from the original guppy tank so whatever is in it in terms of bacteria should be ok... The original guppy tank had guppies in it for about 1.5 years with few casualties. The filter is a bio filter so it should have bactinettes, etc already built up... It was just moved from one tank to the new tank. As for temperature...We americans only do things in degrees F cause nobody here understands Degrees C.... actually that was a generalization... The water is kept pretty much at 75 degrees F.  The only difference in this tank and all of my others is that the tank is taller then it is wide... and it is compact... so I am not sure if the bottom of the tank actually gets filtered... or if some of the water may actually become toxic.  Fish that have gone in that tank always swim around and explore even at the bottom but by the next day they are all at the top around the filter... the day after they are dead.  I added the four plants... and they are large in size to help deal with any kind of toxicity that may form at the bottom.  I also don't fill the tank all the way to the top I leave about 2 inches so that the filter actually drops water into the tank.  That alone should add a lot of Oxygen and there is also a small air stone which I have at the bottom to help move water around, and add oxygen to the lower part of the tank.  This tank has had both guppies and cichlids in it...of course not at the same time, however both types of fish have died after three days. Cichlids are very adaptable to strange water situations and can live in both soft and brackish waters.  Right now I have two tanks of guppies (cause they are so cute), four tanks of cichlids, one goldfish tank, a snail tank (cause they work for free) and a hospital tank (cause I have cichlids.)  So they should all be use to the water conditions here... I rarely have a casualty in any of the other tanks... and if I do its probably due to isolated issues like bad genetics, etc. I can not stress enough that all of the tanks are treated the same... im a virgo...so I do things the same... kinda like OCD... (smile)  got answers?

Answer
Hi Dave,
 Hmm.. that is puzzling.  Some things to consider: gravel. Have you used a different type of gravel in this tank, something that might have a toxin in it?

 I assume that no soap came in contact with this tank or the biowheel.  

 When the fish die, do they die with their mouths open, like they were gasping for air, or with their gills flared out?

 I assume that you are buying the fish from a proper source like a fish store and not from a place like Walmart?

-- Ron
  rcoleman@cichlidresearch.com
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