Troublesome situation

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Aquarist, not Aquarius
Oct 17, 2004
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16
Gainesville, Florida
My second 10-gallon tank has 4 zebra danios and 4 adult paleatus cory catfish right now. It has been set up for 6 months now. I noticed that the cories were not doing well right after yesterday's water change so I checked the pH: 7.2 or so.

They have been flashing along the bottom since yesterday and have been very inactive. They would only move about if I offered them food.

As a part of the cleaning, I scraped down all of the brown algae on 3 sides of the tank, washed out the filters in the old water and gravel vacuumed the entire bottom.

Is there anything you think might be wrong? I know nitrates and nitrite shouldn't be that bad after draining 5 gallons out yesterday. I was very thorough and did treat the water with the fizz tabs that jungle products make. Heck, I even used the same treated water on my other tank for its maintenance and the fish have never been happier over there.

(sigh)

I added a ph buffer to the tank and added carbon to the filter from my other tank. Hopefully the 1-2 combination will help. Any suggestions would greatly be appreciated.
 
You might want to test to see what the Ammonia/Nitrites/Nitrates actually are. Just a water change may not solve the problem if the levels are very high, and depending on your source water, it may have high nitrate levels as well. From my understanding, corys are very sensitive to water problems and will act as an indicator of such problems.
 
One thing you never want to do is a thorough cleaning of the tank all in one day. You can set back your nitrogen cycle enough to where it can no longer handle the toxins for a few days. Never gravel vac the entire bottom of the tank in one water change either. Vac at most 1/4 to 1/3. Next water change do a different section.

"Flashing" usually indicates a parasite such as ich. How does the skin on the cories look? How about the Danio's?
 
You would almost have to try to seriously damage your nitrifying colonies. A thorough cleaning of the tank should not have any negative reprocussions so long as:
it is done routinely (otherwise there will be a significant change in water chemistry)

the temperature of the new water is close to the tank water

water is dechlorinated, in your case you should use a dechlorinator that breaks the N-Cl bond in the chloramines and neutralizes the ammonia released

Filter media are rinsed in tank or dechlorinated water, not fresh tap water

Nitrifier fasten quite securely to the media surface, since they are required to be fastened to a surface to carry out their life processes, they've evolved to be quite good at it.

As for vacuumming, I don't think that a very thorough vacuuming of 100% of the substrate could be accomplished without emptying more of the tank than most people would recomend. Even then, the nitrifiers are in the filter, not the substrate (for the most part, unless you're running a UGF). Yes, there are bacterial colonies that develop in the substrate, heterotrophs mostly, but I think that you would be hard pressed to purge your tank of them completely.

Flashing does sound like Ich, which probably means that the fish have been stressed in some way. Nitrogen titers are a good thing to measure and let us know.
 
happychem said:
You would almost have to try to seriously damage your nitrifying colonies. A thorough cleaning of the tank should not have any negative reprocussions so long as:
it is done routinely (otherwise there will be a significant change in water chemistry)

the temperature of the new water is close to the tank water

water is dechlorinated, in your case you should use a dechlorinator that breaks the N-Cl bond in the chloramines and neutralizes the ammonia released

Filter media are rinsed in tank or dechlorinated water, not fresh tap water

Nitrifier fasten quite securely to the media surface, since they are required to be fastened to a surface to carry out their life processes, they've evolved to be quite good at it.

As for vacuumming, I don't think that a very thorough vacuuming of 100% of the substrate could be accomplished without emptying more of the tank than most people would recomend. Even then, the nitrifiers are in the filter, not the substrate (for the most part, unless you're running a UGF). Yes, there are bacterial colonies that develop in the substrate, heterotrophs mostly, but I think that you would be hard pressed to purge your tank of them completely.

Flashing does sound like Ich, which probably means that the fish have been stressed in some way. Nitrogen titers are a good thing to measure and let us know.
Click to expand...



I use the "start right" tabs which remove the chloramines. At least, that's what the package says. I've used them since setting up my first tank. By saying I vacuumed 100% of the gravel, I ment surface area. It's not a thick substrate since there are no plants growing in it.

I noticed in the past my aquaclear filter will siphon all of the water out of itself as I'm changing the water. Maybe the filter media got too dry and killed off a majority of the colony. I clean the tanks weekly, but never got around to scraping off the brown algae from the tank walls till last time.

These cory catfish and danios have been through everything from 2 1/2 hour road trips, overcrowded tanks, spawnings, to tank cycling. It'd be wierd for ick to manifest itself by now, wouldn't it?

Could they have irritation on their gills from the fluctuating pH? The danios seem to be just as happy as ever.
 
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What are your NH3, NO2 and NO3 levels? I doubt that the filter media died from syphoning out, my aquaclears do that too, as long as you don't leave them too long they should be fine. But the measures of NH3 and NO2 can confirm whether or not you have a problem with your nitrifiers.

The tabs probably just break the NH3-Cl bond but don't likely do anything for the ammonia. In most cases, this isn't a major issue, the freed ammonia will be consumed by your nitrifiers in the same manner as fish derived ammonia. The problem is that you could get a momentary spike in ammonia concentrations at each water change.

As for why Ich might manifest itself now, that's a good question. One possibility is that the parasite was not in the tank earlier, other than water, have you added anything new to the tank recently? While the fish may have survived the various ordeals, they've no doubt been weakened by it, leaving them more susceptible, in general, than fish that have not. But there's no guarantee that this is Ich, so until more symptoms manifest there's no need to speculate.

Sure, could be from pH fluctuations, or from other fluctuations in chemistry. Fish aren't terribly sensitive to pH changes (within a reasonable range, say +/- 0.3), the osmolarity (TDS) of the water is more significant.

Keep up the water changes and be patient. Keep us posted of any new developments.
 
Well, whatever was happening with the chemistry seems to have evened itself out.

The corys stared laying eggs for the past two days and the Danios were more than happy to eat them. None of the cories flash now, so I haven't the foggiest what could have gone wrong.

I'll keep you posted. Haven't been able to get the water tested.
 
Slightly off topic, but I will second the opinion that draining your Aquaclears will not kill too many bacteria.
As a part of my normal weekly tank cleanings, I use the AC intake tube as a guide. I turn off my filters (actually I flip the switch to the power strip everything is conencted to) and vaccum the water out to just below the intake tube on my filters. In 3 years I have NEVER experienced any negative results.
 
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