Cyanobacteria: effects on fish beyond appearance

[bettaMagenta]

I've got a "cyno" issue in my Rainbow tank and it's been taking a toll on my fish, including that deformed spine fish I posted about before - and my barbel-less Cory's are in this tank too. I'm trying to figure out what kind of illness is associated with "cyno". I could go on and on about all the things I was doing wrong with my tank, but the short version is I was trying to grow water lilies, which didn't work out because the water was too alkaline. I had strong lighting to help the lilies and was feeding heavily to promote growth in my severum juveniles.

I don't want to change the lighting hours, though - I like having long hours of light so I can see my fish before and after work. I've already reduced the intensity of the lighting, but kept the hours the same. If I have to, I might consider turning off the lights during the middle of the day. The water's fine and I've only got a little algae, even with the long lighting hours, in my other tanks.

To tackle the issue, I'm removing the pots with dirt and river pebbles that the lilies were planted in, and doing some heavy gravel vacuuming and water changes. I'm wondering if the "cyno" could be causing problems for my Rainbows - and maybe even contributing to my barbel-less Cory's?

[Burgermuncher]

I've been dealing with Cyanobacteria a lot more since moving to my current location. I've found that reducing the lighting hours on two of my tanks to 7.5 hours, from 1330 to 2200 hours, has helped - PAR at the midpoint is around 60. I also make a point to vacuum up any occurrences within a couple of days, usually starting on the gravel before it gets out of hand.

I've also cut back on cleaning the tank, especially the gravel vacuuming. I realized my plants were chlorotic and nitrates were below 5 ppm, indicating a nutrient deficit. I've allowed the nitrates to rise to 5-10 ppm, and while I've got more green algae now, I've got no detectable Cyanobacteria. I suspect the phosphates have also increased, but I don't test for that.

From what I've read on other sites, Cyanobacteria seems to thrive in environments with restricted or excessive nutrients. Since I couldn't reduce nutrients further, I tried the opposite approach and it's worked for me.

Luckily, I don't think my fish suffered from the Cyanobacteria. I suspect the genus I've got is Oscillatoria, based on the stacked cells, shape, and constant motion under the microscope - though I'm not 100% sure on the ID.

[coltin]

Cyanobacteria's a real killer, releasing toxins that can poison anything that comes into contact with it. Fish that live near the substrate, like loaches, catfish, and eels, are more susceptible to these toxins, whereas mid-water and surface dwellers are less likely to be affected initially. That being said, if you neglect regular water changes, the toxin buildup can be catastrophic, ultimately claiming the lives of even the hardiest fish in the tank.

[shakinStevens]

I've been dealing with Cyanobacteria a lot more since moving to my current location. I've found that reducing the lighting hours on two of my tanks to 7.5 hours, from 1330 to 2200 hours, has helped - PAR at the midpoint is around 60. I also make a point to vacuum up any occurrences within a couple of days, usually starting on the gravel before it gets out of hand.

I've also cut back on cleaning the tank, especially the gravel vacuuming. I realized my plants were chlorotic and nitrates were below 5 ppm, indicating a nutrient deficit. I've allowed the nitrates to rise to 5-10 ppm, and while I've got more green algae now, I've got no detectable Cyanobacteria. I suspect the phosphates have also increased, but I don't test for that.

From what I've read on other sites, Cyanobacteria seems to thrive in environments with restricted or excessive nutrients. Since I couldn't reduce nutrients further, I tried the opposite approach and it's worked for me.

Luckily, I don't think my fish suffered from the Cyanobacteria. I suspect the genus I've got is Oscillatoria, based on the stacked cells, shape, and constant motion under the microscope - though I'm not 100% sure on the ID.

I can attest to that, I've had my fair share of struggles with cyanobacteria and micro nutrient deficiencies. Once I got my fertilization regimen dialed in, the cyanobacteria issue just vanished. It's interesting you bring up the toxins, I've read that not all types of cyanobacteria produce them, but the ones that do can be particularly hazardous to certain species of fish, like those that dwell near the substrate. Regular water changes are crucial in maintaining a healthy environment, I'm a firm believer in that. I've noticed that even with a well-balanced tank, the buildup of minerals and salts can still pose a risk to the fish if not addressed through regular water changes.

[Lachlan]

I'm familiar with the green slime issue, but in my case, it shows up on the cover for my LED lighting, not in the water column itself. The cover is pretty much in contact with the water, making it a perfect breeding ground for this stuff. I've found it's not worth stressing over, and I just use a paper towel to wipe it off the light cover when I'm doing my water changes.

[barnicle]

I've dealt with cyno in my tank a few times and it's always been a real challenge. The tank's in a south-facing room with two huge windows, so it gets blasted with sunlight all day, especially during the summer. For me, cyno's always started in the gravel, but I've learned to tackle it by removing and replacing the affected area as soon as I spot it. I also bump up my water change frequency to help get rid of it. I do my best to limit the extra light that gets to the tank and I've found that adding more aeration and water movement really helps to clear it out.