Losing Fish After Fish

[scorer14]

Hi Everyone, I'm new here but need some assistance I keep losing my fish - it seems to always being my guppies however I have started to lose my female betta's.

My water perimeters are all fine, I did a test yesterday but didn't write the results everything was in the normal zone nothing close to being high or toxic.
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Tank size:20 gallons
pH:
ammonia:
nitrite:
nitrate:
kH:
gH:
tank temp:80 degrees

Fish Symptoms (include full description including lesion, color, location, fish behavior):the guppies seem tired, they swim at top of tank. The Betta just stopped eating, but look healthy and the next day or two they are found dead.

Volume and Frequency of water changes:20% every week

Chemical Additives or Media in your tank: salt and add cycle every water change. Are water is high in iron could this cause the deaths. I have a greenish tint to the tank, we removed some driftwood, and have added a UV sterlizer and it is slowly improving with each water change. The tank has been up and running for 5 months. I have live plants and a gravel bottom which is vacumned every week with water changes. I will also note that I have a small tank with a male betta and three neon tetras with no issues at all (same water)

Tank inhabitants:2 female guppies - left, 1 female betta - left, 3 tiny freshwater bumble bee, and 7 platies and two yo-yo loaches

Recent additions to your tank (living or decoration):none

Exposure to chemicals:none

Digital photo (include if possible):

Please give me some suggestions as to what could be causing this and what can I do to fix it. I really don't want to keep replacing fish or losing them.

 

[drobbyb]

It's better if you post numbers. Test results of "Fine" usually turn out to not be fine. Not trying to insult, just speaking from experience. Any ammonia or nitrite is very bad, ignore the toxic rating on the test strips or in tank monitor.

 

[OldMan47]

Welcome to our forum scorer14.
I am going to agree with drobbyb. We often get loose statements about all being fine just to receive an actual value that is not fine. In either case, even if chemistry does turn out to be "fine", I have found that since we only measure the nitrogen cycle in our tanks there is often something else going on that we do not measure. When I am faced with large losses, yes it happens to all of us at times, I do a huge water change. It is not because I find anything wrong with my readings but precisely because I cannot identify the cause. The result is almost always a complete recovery of my remaining fish. When I say a huge water change, I am not talking about a mere 50% change. I am talking about taking the water down so far that my fish are having trouble staying wet and then refilling. I have been known to call it a 90% change but I have no doubt it is probably more than that.