Flashing multiple times

Gemtrox42

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Tl;dr: When fish flash several times in a row, what can this be evidence of, and how can it be narrowed down?

Background: 30 gal tank, lightly planted with gravel bottom, mostly hornwart, duckweed, swords and java ferns, lots of driftwood. My fish are 14 cardinals, 5 pygmy corys and cherry shrimp, two adult mollies and around a dozen fry. Water is 75 degrees, hang on back filter so should be well oxygenated. Water parameters are 7.3 pH, ammonia 0, nitrites 0, nitrates 5, GH 100, KH 100-120. I am using wellwater. I treat the water with aquavitro seed, and aquavitro alpha dechlorinator. Generally, my tank chemistry has been very stable over time, but I have noticed a slight trend towards lower KH (used to be ~140).

So this is going to get a bit complicated, but over the past 2 weeks I have radically changed what I've been putting in my water. Until 2 weeks ago, I was using only salt-softened water, a variety supplements, namely seachem flourish, excel, and iron for my plants, and my tank temperature was at 80 degrees. Since then I have corrected these to what you see above. I am also in the process of increasing my water GH to 300ppm and rehoming everyone other than my mollies to a more suitable tank.

I have noticed my mollies and cardinals flashing on rare occasions since getting them. My understanding is that flashing can be anything from a normal behavior to sign of stress, both of which I imagine probably apply in my case, given the poor water parameters they have been living under. However I noticed one of my molly fry flashing against a small ceramic bowl I use for cory food, doing so 6 or 7 times in rapid succession. Since then I've checked for signs of ich or other external parasites and found none on the fry or any other fish. Hopefully this is not the case, but I wouldn't rule it out, especially if I had some advice from you guys.
 
Could be stress from the water change, how long did you spread out the process of changing the water? How often do you do water changes? Do the fish have red gills or have you noticed any extra slime? Another thing to look for is gill flukes. I know that fast water changes can lead to a drop in ph, do you also dechlorniate your water before adding it to the tank? Just some ideas, I hope your fish get better and it gets figured out!
 
Iv found flashing can be for multiple reasons depending of the fish ( not facts my experience) Iv found that cichlids can flash and flair to intimidate and when breeding , the only time I hve saw my tetra flash was just before a Ich outbreak , strangley enough it only effected the tetra bottom dwellers , iv saw my corys flash I guess normally the day before my water change and vac instantly stops as soon as the change is done and iv never saw my pleco flash at all
 
Usually it's either water issues or parasites.

If you don't have issue with water, then it's due to parasites such as skin flukes, gill flukes, etc.
Gill flukes can kill fish slowly.
At the last stage of gill flukes infection, the fish will breathe very fast and then it will die.
Keep observing your fish for symptom of fast breathing.
If it happens, use Praziquantel or Flubendazole.
But you may have to treat the tank for at least 1.5 month or longer.
Each time the gill flukes return, they will kill more fish and become stronger.

Flubendazole:
https://www.amazon.com/dp/B085TQ75Z5/?tag=ff0d01-20

Praziquantel:

More information:


 
By the way, what do you mean by salt-softened water?
Can you explain more?

Salt shouldn't be used unless for treatment of disease.

Whenever you introduced new fish, you have to quarantine them.
If not, they can carry parasites, bacteria or even virus with them.
 
Could be stress from the water change, how long did you spread out the process of changing the water? How often do you do water changes? Do the fish have red gills or have you noticed any extra slime? Another thing to look for is gill flukes. I know that fast water changes can lead to a drop in ph, do you also dechlorniate your water before adding it to the tank? Just some ideas, I hope your fish get better and it gets figured out!
I do water changes of about 25 percent once a week. I have no chlorine in my water, and my pH is stable. However there is currently salt in my water and the Gh is too low for the mollies. I am working on correcting the last two. I will try smaller water changes as well.
Usually it's either water issues or parasites.

If you don't have issue with water, then it's due to parasites such as skin flukes, gill flukes, etc.
Gill flukes can kill fish slowly.
At the last stage of gill flukes infection, the fish will breathe very fast and then it will die.
Keep observing your fish for symptom of fast breathing.
If it happens, use Praziquantel or Flubendazole.
But you may have to treat the tank for at least 1.5 month or longer.
Each time the gill flukes return, they will kill more fish and become stronger.

Flubendazole:
https://www.amazon.com/dp/B085TQ75Z5/?tag=ff0d01-20

Praziquantel:

More information:


I do have big issues with my water, as mentioned to PorshaF. I would like to be cautious however. Can you tell me how long gill flukes might lay dormant or take for symptoms to appear? I haven't added any new fish in 4 months, so if flukes appear faster than that I might eliminate the possibility.
By the way, what do you mean by salt-softened water?
Can you explain more?

Salt shouldn't be used unless for treatment of disease.

Whenever you introduced new fish, you have to quarantine them.
If not, they can carry parasites, bacteria or even virus with them.
I was using water from a water softener that used salt to exchange ions with calcium, therefore my water is low GH but has some salt. I just found out how bad this is recently and am doing water changes to get the salt out. It could quite possibly be the culprit.

I would like to say in addition that I have heard about quarantines not working because fish only become susceptible to disease when stressed. Do you agree with that sentiment? If not, what would you say quarantines prevent from happening?
 
Have there been any improvements since your first post?
Difficult to say. The behaviors are still occuring, but possibly less frequently now. If there are noticeable improvements they should be within a few days, as I just recently finished getting the salty/softened water out.
 
Hopefully that was the cause and everything returns to normal again, i know how stressful unsolved tank problems are! I once had a dead fish get sucked up into the back of the filter and didn't know and couldn't figure out why I kept getting ammonia spikes until I went to rinse the media ?
 
I do water changes of about 25 percent once a week. I have no chlorine in my water, and my pH is stable. However there is currently salt in my water and the Gh is too low for the mollies. I am working on correcting the last two. I will try smaller water changes as well.

I do have big issues with my water, as mentioned to PorshaF. I would like to be cautious however. Can you tell me how long gill flukes might lay dormant or take for symptoms to appear? I haven't added any new fish in 4 months, so if flukes appear faster than that I might eliminate the possibility.

I was using water from a water softener that used salt to exchange ions with calcium, therefore my water is low GH but has some salt. I just found out how bad this is recently and am doing water changes to get the salt out. It could quite possibly be the culprit.

I would like to say in addition that I have heard about quarantines not working because fish only become susceptible to disease when stressed. Do you agree with that sentiment? If not, what would you say quarantines prevent from happening?

If you have gill flukes, your fish will have the symptoms from the 1st week.
And your fish will start dying probably from 2nd week onwards (depending on how serious is the infection).
The flukes can survive for 1-2 months even with medications. It's very hard to kill all of them.

But if you don't have any fish died for the last few months, then I don't think its due to flukes.

Make a large water change for your tank to remove all salt in your tank..
When I was keeping Discus, I used to change up to 100% of water once a week. My Discus were healthy.
But I got bored with Discus tht I gave them to one of my friends who also keep Discus.
 

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