Guppy in trouble with red spot

My wife’s having trouble with her relatively new tank, today including a Guppy who’s developed a red spot, is not feeding, and is spending most of his time hovering near the surface of the tank. Pictures and details follow.

In spite of frequent water changes, ammonia hasn’t dropped below 1 (cycling the water with spring water testing at 0 before being added to the tank). A few other fish have been lost in the last few weeks with various symptoms, though perhaps many due to a Molly that was aggressive (and was returned to the store a week ago). Tank was treated with Kanamycin about three weeks after attempting to treat the last sick fish.

The Guppy has just been moved to a hospital tank (zero ammonia) with Kanamycin and receiving a separate salt water bath.

Thanks in advance for any and all help.

Tank size: 10 gallon
tank age: 1.5 months
pH: 7.4
ammonia: 1.5
nitrite: 0
nitrate: 5
kH: 40
gH: 75
tank temp: 80F

Fish Symptoms (include full description including lesion, color, location, fish behavior):
Red colored dorsal spot, not feeding, generally hovering near the surface of the tank. Previously some stringy poop. The red spot developed three days ago, the lack of feeding and activity began today.

Volume and Frequency of water changes:
Today (21 Feb) 20%, 14 Feb 30%, 5 Feb to 8 Feb daily water changes ~20%

Chemical Additives or Media in your tank:
Aqua Safe, Stress Zyme

Tank inhabitants:
No other guppies, one adult molly, two baby mollies

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

Exposure to chemicals:
none

Digital photo (include if possible):

The losses will be caused by ammonia poisoning. Ammonia should always be at 0 ppm. If it is still 1.5 then you should remove the fish to a holding tank, replace all of the water, then put them back.

Fish do occasionally get red marks if they are rubbing against objects to relieve irritation and this behaviour commonly occurs in high-ammonia water since ammonia is an irritant.

If you can resolve the ammonia issue with water changes then I’m sure this red spot will clear up.

Thanks a million! We're new owners in the aquarium world and are working hard to figure everything out.

To reset the main tank by doing a 100% water change, should we keep our gravel and filter in place, or swap/clean those items out at the same time? A week ago, even with daily water changes of 20% to 50% 4 days in a row, the ammonia kept reading at least 1 PPM.

BenjaminTX said:

Thanks a million! We're new owners in the aquarium world and are working hard to figure everything out.

To reset the main tank by doing a 100% water change, should we keep our gravel and filter in place, or swap/clean those items out at the same time? A week ago, even with daily water changes of 20% to 50% 4 days in a row, the ammonia kept reading at least 1 PPM.

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I would keep the filter and gravel the same. Beneficial bacteria is housed on the filter. If you have ammonia it means your tank is not cycled all the way. As bacteria breeds it will convert the ammonia in your tank to nitrite then it will take a few weeks for more bacteria to breed that will convert the nitrite to nitrate. Ammonia is very toxic to fish, nitrite and nitrate are not as lethal from what I've heard but its best to keep nitrite at 0 at all times. Nitrate as long as its below 20 should be safe for fish. Keep doing daily water changes of at least 50 percent until your test has 0 ammonia and 0 nitrite.

BenjaminTX said:

Thanks a million! We're new owners in the aquarium world and are working hard to figure everything out.

To reset the main tank by doing a 100% water change, should we keep our gravel and filter in place, or swap/clean those items out at the same time? A week ago, even with daily water changes of 20% to 50% 4 days in a row, the ammonia kept reading at least 1 PPM.

Click to expand...

You should always keep the gravel and filtration media as these contain beneficial bacterial colonies that naturally remove ammonia and nitrites.

When it comes to cleaning the filter and gravel, which you would do weekly if there is no detectable ammonia, you would lightly vacuum the gravel with a siphon and lightly rinse the filtration media in dechlorinated aquarium water. The goal is to remove excess waste, as opposed to removing the above mentioned bacterial colony from any surfaces. Ensure any replacement water is always dechlorinated as chlorinated water is also an irritant to fish and also kills the bacterial colony.

You have mentioned that you keep getting a 1+ ppm reading for ammonia. This is either due to not enough water changes having been done, a dirty filter or you are using a product that has the ”ammonia remover” notice on it which is known to interfere with ammonia test results. To keep things simple I recommend doing 100% water changes anytime you have an 0.1+ reading for ammonia and I recommend purchasing an Seachem ammonia alert card to stick on the aquarium glass.

Once you have reached an ammonia reading of 0 I recommend feeding the fish 75% less so less ammonia is produced. If you have room in your filter, add a small amount of zeolite media which absorbs ammonia.

Check your tap water for ammonia. That could be where it's coming from.

If your tap water is free of ammonia, then do a 75% water change and gravel clean the substrate every day until the ammonia level is at 0ppm.
Make sure any new water is free of chlorine/ chloramine before it's added to the tank.

Stop adding stuff like anti-biotics to the tank. Most fish health issues are caused by poor water quality (ammonia, nitrite or nitrate). Doing big daily water changes for a week will usually fix most problems.

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Kanamycin is an anti-biotic that should not be used unless you have a known bacterial infection that responds to Kanamycin.

Don't use anti-biotics unless the fish have a known bacterial infection that has not responded to normal treatments. Improper use and mis-use of anti-biotics has lead to drug resistant bacteria that KILL people, birds, reptiles, animals and fish.

The following link is me ripping into people mis-using anti-biotics. Have a read if you're brave enough