Sick platies

[EliK]

Parameters:
Tank size: 15 gallons
Age: 3 months since end of cycling
PH: 7.5
Ammonia: 0ppm
Nitrite: 0ppm
Nitrate: 25ppm
Tank temp: 79'F
Volume and Frequency of water changes: monthly, 25-30%

Tank inhabitants:
3 mollies (2 female, 1 male), 2" long
3 small angelfish, >1.5" high
2 platies (1 male, 1 female)
1 golden Chinese algae eater
On Thursday, I added 5 Zebra Glofish, added 1 angelfish, and took out 1 angelfish that I am giving away.
One of the zebras died within a very short time after it was added. I believe it may have been injured when it was put in the bag, but I can't be sure. I removed it as soon as I could, but both platies and one angelfish were nipping at it in the meantime.

On Saturday morning, I noticed that the female platy seemed lethargic - resting on the bottom of the tank, with clenched fins. She has occasionally seemed lethargic over the last few weeks, but not frequently or consistently. This is the first time I saw clenched fins.

By about 2 hours later, both platies developed white spots around their mouths. I removed both to a different tank as soon as I could set one up. A little later, I noticed that the area around their gills was also discolored - in some areas white, and in some areas a metalic golden color.

After another couple hours, the male began swimming erratically - alternately floating freely and zooming crazily up and down the side of the tank, and occasionally swimming upside down. Within a half hour, it was dead.

The female is still lethargic, and sitting with clamped fins.

Picture of the dead male: Note the coloring around the mouth. This is how it looked before it died as well.

 

[MrDankYT]

Sounds pretty alarming but i'm not sure what it is, but i don't think you should have angelfish in your aquarium, they are a schooling fish but even if it was in a school 15 gallons would be way too low for it.

 

[nic1]

Hello.... So you've changed the water three times since the tanks been cycled...... I'd suggest upping your water changes to once a week and at 50%
I change 10% of my water every morning now and ive had happier fish (Egg laying, playing, active) where I've had problems in the past doing small water changes over a longer period of time.

Fish are more supceptable to bacterial infections when the water quality isn't up to scratch. As a general rule, when ever a fish dies or seems sick I always carry out a major water chge of three quarters.

 

[EliK]

For the first two months I was changing the water almost weekly. It was only for the last month that I dropped down to once, because all the parameters were completely level and everything seemed fine.

 

[Essjay]

We need to do water changes regardless of the levels shown by or test kits. They can only tests for a very few things, and fish excrete/secrete many more things that we can test for.
Testing for ammonia and nitrite just tells us whether we have enough micro-organisms to cope with the ammonia made by the fish. Nitrate tells us how much ammonia is being converted, after we have subtracted the level in our tap water.; we should aim to keep that below 20 ppm.

But the things we can't test for will build up in the water, and we need to remove them by large weekly water changes.