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Had an odd occurrence last night and I'm not sure what may have caused it. After water changes last night my sterbai became lethargic and I lost 3 of the 10 during the night. Water parameters are good, pH 6.5, NH3 and NO2 are zero and NH3 is nearly undetectable. My water source is RO treated with RO Right and Discus Essentials (trace elements) to a TDS of 60 ppm (EC 28.2 µS). Tank temperature is 82 F and the new water was 80 F. The tank is a 20 gallon long (30x12.5x12") and the 10 juvenile sterbai, now 7, are the only inhabitants. I do frequent water changes in all of my tanks, 25-50% no less than 5 times per week.

I conducted water changes with the same source water on 3 other aquariums, one containing 6 C. trilineatus, one with 6 C. reticulatus, and one with 6 C. loxozonus and a pair of Mikrogeophagus altispinosus and had no signs of distress or losses among them. Any ideas why the sterbai reacted as they did?

A quick question but why are you changing the water so much? I'm not familiar with RO myself, for my sterbais I do a 30% WC with regular treated (prime) tap water on a 60G with around 40 sterbai (juvies to adults) tank is at 78F (room temp) and mine are flourishing.

Supercorygirl wrote:A quick question but why are you changing the water so much? I'm not familiar with RO myself, for my sterbais I do a 30% WC with regular treated (prime) tap water on a 60G with around 40 sterbai (juvies to adults) tank is at 78F (room temp) and mine are flourishing.

Just habit from keeping discus, no such thing as too little nitrate in the water.

Something similar happened to a friend of mine in our local club. We never really figured out the cause.

http://www.capitalcichlids.org/forums/s ... ostcount=1

Some theorized that it was due to "self-poisoning", which Corydoras in general and Sterbai in particular exhibit, but others were skeptical.

You might read through the thread to see if you see any common facts.

MChambers wrote:Something similar happened to a friend of mine in our local club. We never really figured out the cause.

http://www.capitalcichlids.org/forums/s ... ostcount=1

Some theorized that it was due to "self-poisoning", which Corydoras in general and Sterbai in particular exhibit, but others were skeptical.

You might read through the thread to see if you see any common facts.

The behavior was similar, they became lethargic and several just floated in the current without resisting. I see no signs of fin rot or other disease, nor are any of the nitrogenous waste levels elevated like in your friends case. This might be one of the weirdest things I've seen in my 20+ years of fish keeping. Typically during a water change they become very active, playing in the current and digging for food. I've heard of bad reactions when water quality in the tank is very poor and the fish are shocked by the sudden influx of clean water but with my water change schedule and near undetectable waste levels that can't be the case. I guees I'll just chalk it up to weird shit that happens when you keep animals.

Just to have thought of everything - how long was the water treated with oxygen?

All RO systems remove all oxygen from the water, and therefore RO water needs some 24 hours with air bubbling through it in order to get the oxygen dissolved and make the water usable for fish.

I think you normally do this - from what you wrote I get the idea you always use RO water, but perhaps this time you did not wait as long as usually?

Bas Pels wrote:Just to have thought of everything - how long was the water treated with oxygen?

All RO systems remove all oxygen from the water, and therefore RO water needs some 24 hours with air bubbling through it in order to get the oxygen dissolved and make the water usable for fish.

I think you normally do this - from what you wrote I get the idea you always use RO water, but perhaps this time you did not wait as long as usually?

You are correct that I always use RO water. I have never aerated the water before use, but I do have an airstone in each aquarium. I have never heard of RO systems removing dissolved gases from the water, and all sources I can find state that they do not effect O2 levels.

I don't know for sure, but I think the self-poisoning theory doesn't hold true in a larger amount of water. I thought that only had negative effects when the fish were in a small amount of water (like a bag). The toxins dissipate to non-harmful levels in more water - I think.

Do the other 7 seem normal and healthy? Could it be a cause besides the water change - internal parasite for example?

As SuperCoryGirl stated - I don't know if using pure RO for Corys is the best plan. I use a 50/50 RO/Tap mix to remove some of the hardness in my Tap water - which has been as high as 11 degrees Gh. It also helps bring the PH down to acceptable levels -7.1 to 7.3 range as opposed to 7.8 to 8.1 from the Tap. I'm keeping 46 species of Corydoradinae in my fishroom right now, and rarely lose a fish - Corys are pretty tough little fish once they've settled in! Just seems strange.

rmc wrote:I don't know for sure, but I think the self-poisoning theory doesn't hold true in a larger amount of water. I thought that only had negative effects when the fish were in a small amount of water (like a bag). The toxins dissipate to non-harmful levels in more water - I think.

Do the other 7 seem normal and healthy? Could it be a cause besides the water change - internal parasite for example?

As SuperCoryGirl stated - I don't know if using pure RO for Corys is the best plan. I use a 50/50 RO/Tap mix to remove some of the hardness in my Tap water - which has been as high as 11 degrees Gh. It also helps bring the PH down to acceptable levels -7.1 to 7.3 range as opposed to 7.8 to 8.1 from the Tap. I'm keeping 46 species of Corydoradinae in my fishroom right now, and rarely lose a fish - Corys are pretty tough little fish once they've settled in! Just seems strange.

The remaining 7 are back to normal. I am skeptical of internal parasites causing a post water change freak out, and they have good body weight and normal looking feces. I am not using pure RO, it is reconstituted with RO Right and Discus Essentials mineral supplements. The tap water here is very strange, soft (2° KH, 3° GH), pH around 8.2 and treated with chloramine so I would rather not use it in my aquariums. It really was a strange event and has me baffled.

Tony C wrote:

Bas Pels wrote:Just to have thought of everything - how long was the water treated with oxygen?

All RO systems remove all oxygen from the water, and therefore RO water needs some 24 hours with air bubbling through it in order to get the oxygen dissolved and make the water usable for fish.

I think you normally do this - from what you wrote I get the idea you always use RO water, but perhaps this time you did not wait as long as usually?

You are correct that I always use RO water. I have never aerated the water before use, but I do have an airstone in each aquarium. I have never heard of RO systems removing dissolved gases from the water, and all sources I can find state that they do not effect O2 levels.

An RO apparatus is basically a very fine filter - it filters out everything which is larger than a H2O molecule. O2 is an example of such molecule - it is much larger than a water molecule.

Many people do not realize this - RO water from the apparatus is basically free of any dissolved gas. If you normally prepare the water on monday, use it on tuesday, prepare water on wednesday and so on, you were Lucky the water 'sucked' the oxygen in. However, one day, something went wrong. Or you started early

it is reconstituted with RO Right and Discus Essentials mineral supplements.

I forgot about this - yes the RO Right alone should be enough. I would be doubtful of internal parasites too, just a thought.

@Bas Pels - TonyC is just doing water changes with the "new" RO water, not completely immersing the fish in it - Shouldn't there be enough dissolved O2 in the rest of the old tank water?

TonyC how are you adding the new water in after water changes? I've heard somewhere that it helps to point the flow of water directly onto a surface (sides of the tank, piece of slate, even a floating plate on the top of the water) the reason for this I can't exactly remember, but it had something to do with gas/air bubbles- if they weren't broken up - it could get trapped in the fish's gills and kill them. I've never actually see this happen - but I always add the water by aiming the flow right at the tank side. Maybe someone smarter than me can explain it better. ;)

rmc wrote:

it is reconstituted with RO Right and Discus Essentials mineral supplements.

I forgot about this - yes the RO Right alone should be enough. I would be doubtful of internal parasites too, just a thought.

@Bas Pels - TonyC is just doing water changes with the "new" RO water, not completely immersing the fish in it - Shouldn't there be enough dissolved O2 in the rest of the old tank water?

TonyC how are you adding the new water in after water changes? I've heard somewhere that it helps to point the flow of water directly onto a surface (sides of the tank, piece of slate, even a floating plate on the top of the water) the reason for this I can't exactly remember, but it had something to do with gas/air bubbles- if they weren't broken up - it could get trapped in the fish's gills and kill them. I've never actually see this happen - but I always add the water by aiming the flow right at the tank side. Maybe someone smarter than me can explain it better. ;)

I pump or siphon the water in and direct the flow over driftwood to break it up. I believe I just discovered the source of the problem, I tested the output from my RO unit and it is allowing ammonia to pass through! I didn't realize it because the biofilters were dealing with it quickly enough that I never saw it while testing tank water. I suspect that the sudden influx of ammonia during the large water change that preceded this event may have shocked them. Looks like I will have to add a DI stage to my RO unit. I miss my tapwater back in Oregon, it was perfect out of the tap unlike the chloraminated garbage water I have now.

Sorry to hear that! You're making me want to go home and test my RO Water

rmc wrote:Sorry to hear that! You're making me want to go home and test my RO Water

Now that I know the problem I can fix it, just hate to see my fish pay the price for my mistaken assumption that my RO unit would deal with chloramine.

Your problem brought back bad memories from many years ago. The point for your thread is that the town I lived in would 2-3 times per year 'clean out the pipes' by putting a large amount of chlorine into the water without prior notification. It maxed out the test strip. I lost fish the first time but after that I would check the water before doing a water change.

I hope you found the cause and the fix is not to much extra work.

I hate when they do that! I am lucky enough that a lfs I patronize sends out email warnings when it happens because they test their water daily. More fish stores should do this I think.

ammonia is a tiny molecule indeed

Sorry to hear that's what killed your fish

mite be worth treating the ro water with prime as a preventative as it detoxifies ammonia nitrite and nitrate.

glad u found the problem. may be time for a new ro cartridge.

personally ide cut half the water changes out as you can actually have too clean water.