Tank die off

[Fish eagle]

55 gallon fresh water tank running nearly problem free for 10 years. Population 7 clown loaches, 2 zebra loaches, 1 zigzag eel. 1 angel, 3 swordtails and a pleco. First week all loaches became sluggish, the second week they started to die. It took only 1 week for all 9 loaches to die. the other fish showed not sign of distress of illness. After the first fish died I did a water exchange, turned on the air stone continuously, treated the water with API Melaflex (cajeput oil) and Prazipro (praziquantel). My loaches continued to struggle to breathe. Their gills pumped water rapidly while they demonstrated no other movement. The dead ones had swollen gill membranes looking like pink smooth tissue. I never was able to see any parasites or flukes on the gills. Finally by the end of the second week my eldest clown loach, a magnificent fish, I had kept for eleven years died.
I have only theories of what and how this evil organism got into my tank. Can anyone provide me some insight.

 

[Autumnsky]

Welcome to the community. It is with great sorrow to hear of the deaths of your beloved Clown Loaches. They are part of the family and are loved. A loss like that is a big and difficult thing to have happen.

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Maybe we can narrow it down.

Did you check the water parameters before, during or after the die off? If so what did you find?

Changing the filter pads/media can cause a problem because the beneficial bacteria is removed (or washed out in untreated tap water), causing a tank to have to re-cycle. Did that happen in the month before the illness/deaths?

Knowing what the water parameters were - and are is important...
Ammonia
NitrIte
NitrAte
pH
GH/KH
TDS

Water temperature

Also if you did any changes in routine, like vacation, huge water change,
adding new fish
or plants or media,
and or did you change food or water treatment products?
Or medications treatments.
Using a new or old or different bucket or was in an area could have caught some spray of bug killer, cleaners, etc.(if you use buckets)?

 

[Fish eagle]

Tank die off, water was good.

Thank you Autumsky for your response. The water was tested during the middle of the die off at my aquarium store. All parameters were good. I started keeping fish 13 years ago and have learn much from experience and reading about maintaining a living environment in a tank. The problem I surmise by observation was a gill disease. The tank was medicated with both antibiotics and against protozoa. My Clowns were likely too advance in the disease process to survive.
This is only speculation on my part. I still seek answers. Should I be posting on the general discussion page to seek a large audience?

 

[King Fisher]

What are you asking exactly? It seems you already answered your own question as to what was wrong with your fish.

 

[Fish eagle]

OK, well let me spell out some questions to help clarify my continue concern. First, I know what happened but not why. I am asking if anyone has experienced similar problems with the specifics my fish suffered. Only the Loaches were effected. It demonstrated gill dysfunction and changed the morphology of the gills.
Has anyone a suggestion in what kind of organism attacked my fish?
What kind of actions can I take to prevent further reoccurences?

I hope King Fisher that I would be mistaken to believe your post was philippic, non-constructive, snarky sarcasm.

 

[Mikesmmrs]

I read that loaches are usually the first affected by ick. Which also affects gills

 

[King Fisher]

Actually it wasn't sarcasm and it wasn't snarky. You said you know what killed your fish. An advanced protozoa that you medicated for. You describe the symptoms of your fish and why you believed it was ill and what you did to help the fish.

But now that you clarified, I understand that there's questions about what may have actually killed your fish. Yes, I'll try my best to help.

Based on the behavior of your fish before death and possibly both the opercula spread open giving the appearance of swollen gills, I'd say they have gill worms. The only way you'd know this is from examining the gills under a microscope. This is also the only way to know what type of worms they had. The most common is probably hookworms.

Gill worms can come from newly added fish, overstocked tanks, live foods. I'm sure there's other possibilities.

The other issue could be chemicals/toxins in your water that cause the gills to swell and stick together. But I'd assume your other fish would have been affected if it was this.

Another idea.....it could have been bacterial gill rot. Gill rot can be caused by a number of things. It can come on from Columnaris bacteria or the result of a worm infestation.

If the gills were light pink accompanied by rapid breathing then death it could be that they suffered from ammonia poisoning.

As you can tell there is many possibilities. Taking a stab at what is wrong with your fish without seeing it before and after death, not to mention we aren't fish doctors, is at best a guess. With that said, I'd lean towards a gill worm of some sort that anchored onto your loaches.

I think Formalin is pretty standard for treatment.

 

[Fish eagle]

Great information

Thank you for your reply. Very informative and shows your knowledge in fish husbandry.
I apologize for assuming any ill intend in your first response. I am still upset about and over sensitive to the loss of my 'old king of the tank.
Thank you again.

 

[Autumnsky]

Did you feed any live worms?

Sometimes they are cultured in house and under good conditions, and sometimes they are received from wild and less than ideal growing conditions and can bring in bad things. Just a thought too.

 

[King Fisher]

No problem Fish. Just keep an eye on your other fish for similar behavior. It might be worth medicating your tank. Seachem Paragaurd is a less harsh med than Formalin and is used to treat different types of worm infestations. Two other meds to use to cover a broader base since we aren't sure what they died from would be Prazi Pro and Metroplex. All three of these meds won't kill off the beneficial bacteria in your tank either.

Sorry about your loss. Just make sure to quarantine any new fish before adding them to your main tank. You can also medicate any new fish in quarantine with the meds I suggested for peace of mind and as a good practice. Some people don't like to medicate but if you aren't 100% positive about the conditions your new fish come from then it might be a good idea. Especially when you are adding them to your community of long standing fish.

Also, get yourself an API Freshwater Master test kit and test your own water. Then you know it's done correctly and you can test periodically and fast when a problem rears it's head.