Tank problems…

[Oli]

So I was recently away for 3 weeks due to surgery and left my partner to look after the tank and have come back to a few problems. She did 2 water changes during that time (30% with a gravel vac at the same time). Since coming back, 2 of my Angelfish have showed subtle signs of dropsy. They are a little bit wonky and buoyant but certainly not the worst I’ve seen. There was also a massive algae build up and the tank is sat at 30+ degrees (UK Heatwave.) Today I did a 40-50% water change as well as a really good vacuum of the gravel while kicking up some of the substrate and cleaned all the gravel. I also cleaned all the algae and it was looking really good and clear again. A few hours later it is starting to look a little bit cloudy for the first time since setting it up. The angelfish are also hanging around the top and gasping for air occasionally. I am worried she may not have disturbed the substrate as much as I normally would and now I have done it properly, I have released some things into the tank.

To summarise the problems atm, the angelfish have signs of dropsy, as well as gasping for air. The rest of the fish are not schooling and are glass surfing, and the tank is a little bit cloudy. There is good surface agitation and I am trying to keep the curtains closed due to the heatwave. Is there anything I can do to help!

 

[Naughts]

Can you give a bit more info?-Test results, tank size and stocking, and how long it has been set up please.
Don't worry too much about the heat, if you can leave the light off and add more oxygen that will help.

 

[Oli]

0,0,30-35
55 US gallons
2 Angel, 10 Congo Tetra juveniles, 4 EBA juveniles

 

[Naughts]

Sounds good. They may be stressed from a combination of the warmer water, the change in cleaning regime and a slight imbalance with the tank since your water change/ gravel clean. Dropsy is a symptom of organ failure not a disease in it's own right.
I recommend daily 75% water changes for a week or two in the hope that it will allow them to recover. The heatwave will be over soon which will eliminate one stressor.
In the meantime try to get some video/ photo of the affected fish and post here to see if anyone can spot anything conclusive. And if there are any new/ worsening symptoms please post the update.

 

[Byron]

What is the pH now, and what was it before all this occurred (i.e., what was the usual pH reading)? And did you happen to test pH when you returned but before the water change?

If the substrate cleaning is a vacuum with the water changer, anything in the substrate is going out of the tank, not into the tank itself, so that should pose no issues.

I assume 0, 0, 30-35 are the numbers for ammonia, nitrite and nitrate, in that order? Why are nitrates at 30-35...is this solely from the tank or are there nitrates in the tap water?

 

[CarissaT]

The warmer water is the less oxygen it can hold. Two 30% water changes in three weeks should have been fine, unless she was way over feeding. That might have thrown the balance off.

 

[Colin_T]

Post pictures and video of the fish.

Are the angelfish eating well?
What does their poop look like?

Did you dechlorinate the new water before adding it to the tank?
Do you have chlorine or chloramine in the tap water?

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Maybe add another dose of dechlorinator to make sure there is no chlorine or chloramine in the aquarium.

Increase aeration/ surface turbulence to help maximise the oxygen level in the water.

 

[jaylach]

Just going by the 'gasping' at the top, did the person dechlorinate the new water during the water changes?

 

[StevenF]

The warmer water is the less oxygen it can hold. Two 30% water changes in three weeks should have been fine, unless she was way over feeding. That might have thrown the balance off.

Additionally algae tends to reduce oxygen levels. So Algae plus heat could cause everything you are seeing. I would put in a air stone with air pump to try and boost oxygen levels and increase water surface agitation to help increase gas transfer between the air and water.

 

[jaylach]

Additionally algae tends to reduce oxygen levels. So Algae plus heat could cause everything you are seeing. I would put in a air stone with air pump to try and boost oxygen levels and increase water surface agitation to help increase gas transfer between the air and water.

In no way saying that you are wrong but could you explain how algae reduces oxygen? I know that some forms, such as 'red tide' in Florida, will kill fish but the majority of the oxygen we breathe comes from ocean algae.

 

[StevenF]

In no way saying that you are wrong but could you explain how algae reduces oxygen? I know that some forms, such as 'red tide' in Florida, will kill fish but the majority of the oxygen we breathe comes from ocean algae.

When you have a lot of algae you also have a lot of dying algae. And when it dies it starts to decay and bacteria eat it. The bacteria need oxygen. And when you have a lot of algae in the water you end up with more organics and more oxygen consumption.

Red tides are different. Some algae also produce deadly chemicals. So when you have excessive growth of a bacteria that produces a toxic chemical. That toxic chemical plus can kill fish and other animals. Most algae don't produce toxic chemicals.

 

[Colin_T]

Healthy algae that is growing will produce oxygen when it gets enough light just like plants do. At night or when it's dark, the algae will use some oxygen and release a bit of carbon dioxide.