In memoriam

Seriously, one of the few highlights since my wife died was buying ten juvenile discus in Auckland last Christmas. Watching them grow over the past six months has been a delight. What hasn't been a delight is the algae in the tank. I never had an issue with my previous tank - in the same location - so I struggled to understand what was going wrong. 

Last month I bought a CO2 setup on the premise that if the regular plants grew faster, they would deprive the algae of nutrients. Sadly, it didn't help--the plants grew faster but the algae grew even faster.

I do a weekly water change (which, if I'm honest, isn't often enough for discus) and scrape off the algae. This weekend was going to be very busy -- I was going to be away, running from one task to the next -- so I wanted to do the water change before I left. That went fine but I also decided to lower the light levels to see if that would help with the algae, and while I was fiddling with the light timers I saw the CO2 wasn't flowing.

The CO2 valve has a "bubble counter" so you can visually see the rate of the CO2. Normally it's 2-3 bubbles per second, but when I looked I didn't see any, so I opened up the valve. That's when I realised the problem was there was no water in the bubble counter, so the CO2 was flowing but I couldn't see it. What I should have done was turn off the valve, add some water and adjust the CO2 back to 2-3 bubbles. However, I was already running late so I guessed at the rate and left.

That evening my flatmate sent me a photo of the discus lying on their sides, breathing but not otherwise moving. At first I thought maybe I didn't use enough water conditioner so I asked my son to add some. I googled some discus discussion groups but couldn't find anything relevant that would explain the fish being on their sides.

In the morning there was no improvement, so I tried to rearrange my day so I could come home between tasks, but it just wasn't going to work. It was about that time that it finally hit me that the problem was likely the CO2. For reasons someone else will have to explain, an excess of CO2 causes the pH to drop. It basically acidifies the water! I asked my son to shut off the CO2, which he did, but obviously that was about 18 hours late. 

When I finally got home Sunday at 9pm, the first thing I did was pull out all the plants so I could see the fish. Five of the discus were already dead. The other five I put in my quarantine tank, along with 4 Sterbai catfish and 2 upside-down cats. I tried to increase the pH of the quarantine tank but I misjudged and went too high. 

Meanwhile I did a big water change on the main tank, cleaned it up and replanted it. The pH was normal (about 6.5) but the water wasn't quite hot enough. I started putting the tank water in the quarantine tank and suddenly three of the discus perked up. Unfortunately, the other two discus had died.

At 2am I reintroduced the fish back into the main tank. The catfish seemed ok and two of the discus were upright, with the third one still struggling. I turned out the lights and hoped for the best.

To say I'm gutted would be an understatement. I know they aren't cats or dogs, but a fishkeeper is responsible for every aspect of the fish's life. After all, they did not evolve to live in such an unnatural habitat. So losing them doesn't feel like losing a pet, it feels like you murdered you me pet. Or in this case, seven of them.

I'll bury them in the morning.