fishtank that kills fish

Question
Hi Tom:

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?

Answer
Hi David,

First off I haven't got any readings in terms of ammonia, nitrites, nitrates and pH. Also I guess you mean 75F as 75 degrees would literally boil your fish alive.

Was this tank cycled before the fish were added? or alternatively were bactinettes added in a media filter bag??

I'm swaying towards your filter here. Try getting hold of bactinettes from your local fish shop. Remove your carbon pad from your filter and place the bactinettes inside with a media filter bag. These should be added along with your fish. Bactinettes will keep your nitrites, nitrates and ammonia down.

Also get a pH test kit, should your water be too acidic try a mixture of marble/ dolomite chips combined with a zeolite pad in your filter. This combined filter removes waste and raises pH.

Should your water be too alkaline you have two options.

a) use a peat filter

b) add monosodium dihydrogen phosphate or dilute phosporic acid. This will reduce alkalinity without affecting the hardness of the water. Always use such additives with care, particularly phosporic acid which should be added to the water in drops to avoid rapid pH changes.

Also do you have any dH readings???

Guppies are uncomfortable in soft water.

As for your algae eater it depends entirely on what it actually is. Bristlenose Catfish (Ancistrus spp.) aren't particularly bothered about pH or water hardness which makes them highly adaptable. Other species such as King Tigers are more delicate and require higher levels of care.


--------------------------------------------------------------------

Another question....was the water aerated and left to stand for 24 hours prior to use???

chlorine, which is added to water by water companies as a disinfectant is not suitable for keeping fish. Chlorine can react with ammonia to produce chloramines. Some water companies actually add chloramines to their water, this is definitely not suitable for fish. Chloramines can be removed by letting the water stand for a few-days prior to introduction to the tank.

In terms of aeration, this is a difficult one. Air can be added to water by the outlet pipe on the filter, however, this is a noisy process. Having the water surface nice and rippled by the outlet can provide high oxygen levels as well.

My advice would be to use the bactinettes, if your planning on keeping guppies make sure that you provide good vegetation and outnumber males with females.

Good luck, and if this is not quite what you're looking for please e-mail me again, so I can look into it further.