Why are my freshwater aquarium fish dying?
This is my story…
About three months ago I got an aquarium… I have Guppy’s, neon tetra’s, swordtail’s and some black Molly’s…
Since I started up I’ve had a really hard time keeping them alive… I have read books on common diseases, but I can’t find anything that I feel match…. I have tested the water many times, and it seems perfectly fine… The temperature is right.. and there is good circulation in the water….
I have a 100 liter aquarium and about 20 – 25 fish…
I find about two dead fish a week! 
And I sort of know who’s going to die .. Cause they start acting weird a day or two before they die….
Symptoms: Some are resting on plants, hiding, resting in the water surface…Resting on the gravel… Some seems to be itching… And they don’t swim much around… And they don’t eat that much either…
Earlier I have diagnosed them for, and treated them for: White spots, (apr. a month ago)
Fungus (only one fish was affected) and that was the first week when I got them..
Now I have a guppy female that is “turning grey”.., I just noticed this morning… And found my 8th dead guppy this morning, and actually I found 2 dead yesterday…. No molly’s, swordtail’s or neon tetra’s have die… Only my favorites…. – The Guppy’s!!!!
Oh, and some of the sick fish have also had tears in they “tail fin”….
Only one or two fish are sick at the same time.. And the others look and act normal.
-I also change the water regularly…
I am now treating them with something called Omnipur – (Sera) . (It’s suppose to kill off several diseases).
Im getting really tired of loosing fish… they cost like 37 norwegian kroner. or in us dollar that would be like 6.2 dollars for just ONE fish…. (Guppy)…….. I should really move to a cheaper country.. hah!!! 
The medicine cost me 119kr = $19.94. Expensiveee…
So pretty please help me! ㋡♥
(And yes, you are correct… this is not my native language, so excuse my possible spelling faults) ;o)
Ps. If you cant answer, – then DON’T!!!!
Thank you!
Hi
You have said that your neons haven’t died?
neons will usually die first if there is something wrong with the water.The smallest fish usually go first as they have less body mass to cope with poisons
I would recommend getting a new ammonia test kit from the busiest store you can find so that it is as fresh as possible and test the water. I think it is probably OK but its worth checking
Assuming the guppys are dying but not the neons suggests that there is something wrong with the guppys. Did you get them all from the same source? Inbred guppys are prone to viral diseases and that may be what is wrong with yours and there is no real cure it will simply run its course
If other fish species are dying too then I would try a new test kit and a thermometer to check the temerature
My best guess is that your fish have velvet, which is a parasite disease a bit like ich, but you usually won’t see any white spots. It’s sometimes known as gold rust disease, but this gold rust does not always show up. The itching, loss of color, lethargy, etc. is all a fit for velvet.
1) Do a 25% water change and increase the temperature in the tank 2-4 degrees (to a maximum of about 82) to make the parasite go through its life cycle faster. It is only susceptible in a certain stage, and the temperature helps it get there faster. You can add up to 1 teaspoon of aquarium salt per gallon if you want. Some people say this helps. I’m not so sure, but it also doesn’t hurt.
2) Remove your carbon filter.
3) Treat according to the directions with a copper sulfate product. Treat for the entire course of treatment.
4) Wait a few days after the treatment is entirely over. Do a 25% water change. Put your carbon filter back in. Turn the temperature back down to normal over a few days.
The fish you are buying from the store may already have this disease, so don’t add any during the treatment period. When you do buy more fish later, quarantine them to see if they show signs, or preemptively treat with the copper.
Also, while your tank isn’t too overstocked, the bioload in your tank is probably pretty high. You might want to reduce the number of fish so the water quality stays high, especially while you try to get a handle on whatever is happening in your tank.
Let me know if this doesn’t sound right, or if you have any other questions. Check the website I’ll link below and make sure it sounds like what’s happening to your fish.
you probly washed your tank with soap
You need to buy a bottle of PRIME. Its a red bottle. It helps lower your NITRITE. and helps level everything else out. Thats what i use and my fish was doing the same thing until i went to my pet store and they helped me out. Pet stores use PRIME as well in their tanks too.