Help! My New Fish Are Struggling ---Flukes?—What Should I Do?

[James_R]

Hey everyone,

I could really use some advice regarding some serious issues with my recent fish order and tank losses. Here’s the full story:

Two days ago, I received a group of fish, including:

• Dwarf Neon Rainbowfish x2
• Emperor Tetra x12 (+2 extra, so 14 total)
• Rummynose Tetra x9 (+1 extra, so 10 total)
• Otocinclus x6
• Dwarf Gourami 3x

I have a 75-gallon main planted freshwater tank and a 20-gallon long quarantine tank. Both tanks have stable water parameters: pH 7.0, temperature 80°F, with ammonia, nitrite, and nitrate all at 0. The quarantine tank has an Aqueon HOB filter with cycled media from my main tank, floating pearlweed, and an air pump for extra oxygen. I acclimated the tetras, otos, and rainbowfish by floating the bags for 15 minutes and drip-acclimating them for about an hour before adding them to the quarantine tank. The dwarf gouramis went directly into the main tank.

One of the otos appeared adult-sized, so I decided to add it to the main tank directly instead of the quarantine tank.

Unfortunately, I wasn’t aware that the fish arrived in breather bags, which shouldn’t be floated during acclimation as it can block oxygen exchange. Despite what I thought were proper precautions, I lost both dwarf neon rainbows and 5 out of the 10 rummynose tetras yesterday. They showed swim bladder issues, which I initially attributed to the stress of shipping or acclimation. The remaining rummynose tetras weren’t eating, and one was breathing heavily. Meanwhile, the emperor tetras and otos didn’t show the same symptoms—they remained active and were eating as usual, though I did notice the otos had red-tinted gills, which is concerning and not normal.

Today, things worsened. I came home to find one of my Boesmani Rainbowfish dead in the main tank with a fuzzy body and enlarged gills. I remembered that the otos, including the one I placed in the main tank, had pinkish gills when it first arrived, but I didn’t think much of it then, assuming it was natural coloration. Now, several of my fish, including the Boesmani and Dwarf Neon Rainbowfish, and the new gouramis have developed slightly enlarged, red-tinted gills—a clear sign that something is wrong.

Additionally, I lost two male Cherry Barbs and a small platy from the main tank. They were found near the filter inlet, bloated around their gills and belly.

In the quarantine tank, another Rummynose Tetra has died, and one of the remaining four has developed swim bladder issues, along with rapid fin rot that I noticed about 2 hours ago. The rest of the Emperor Tetras and otos in the quarantine tank seem active, but the red gills on the otos are still a bad sign.

I dosed PraziPro today an hour ago, suspecting gill flukes. I’m beginning to believe the swim bladder problems and fin rot could be secondary infections caused by the stress of gill flukes. I’m feeling overwhelmed by all these losses and regret adding the oto to the main tank without quarantining it first. I’ve dealt with columnaris and camallanus before, and I promised myself I wouldn’t skip quarantine again—but here I am.

Has anyone experienced something similar? What else can I do at this point? Any guidance would be appreciated.

Fish Losses: Day 1:

• Dwarf Neon Rainbowfish x2
• Rummynose Tetras x5

Day 2:

• Boesmani Rainbowfish x1
• Cherry Barbs (male) x2
• Rummynose Tetra x1

Thanks for any help!

 

[Colin_T]

When was the last time you did a water change on the main tank?
How often do you do water changes and how much do you change?
Do you gravel clean the substrate when you do a water change?

Do you dechlorinate the new water before adding it to the aquarium?
Do you have chlorine or chloramine in your water supply?

What sort of filter is on the aquarium?
How often and how do you clean the filter?

----------------------

This isn't caused by gill flukes. Gill flukes are small flatworms that live on the fish's gills and feed off their blood. Fish can live for months or years with gill flukes and only die from lack of blood if there are lots of flukes on their gills. The gill flukes can also cause scar tissue on the gills and this makes it harder for the fish to breath, but it takes more than 2 days to be an issue.

The Melanotaenia boesemani is covered in excess mucous (creamy white film over entire head, body & fins), which is produced by the fish when something in the water is stressing it out. This is normally water quality related (ammonia, nitrite or nitrate), or some sort of chemical in the water that is irritating the fish.
You need to test the water for ammonia, nitrite, nitrate and pH and post the results in numbers here.

The pink around the gills on the fish and slightly flared gills is normally caused by poor water quality (ammonia, nitrite, nitrate) or low oxygen levels in the water. This can happen when the fish are in the bag being transported to your house (for the Otocinclus) and the fish are in the bag for a long time or they weren't purged (withhold food) for 24 hours before packing.

The bloated cherry barb is probably dropsy and not a swim bladder issue.

If you post a video and pictures of the remaining fish it might provide more information. Upload videos to YouTube, then copy & paste the link here.
If you use a mobile phone to film the fish, hold the phone horizontally (landscape mode) so the footage fills the entire screen and doesn't have black bars on either end.

----------------------

BASIC FIRST AID FOR FISH
Test the water for ammonia, nitrite, nitrate and pH. Post results in numbers here.

Wipe the inside of the glass down with a clean fish sponge. This removes the biofilm on the glass and the biofilm will contain lots of harmful bacteria, fungus, protozoans and various other microscopic life forms.

Do a 75% water change and gravel clean the substrate every day for a week or until the problem is identified. The water changes and gravel cleaning will reduce the number of disease organisms in the water and provide a cleaner environment for the fish to recover in. It also removes a lot of the gunk and this means any medication can work on treating the fish instead of being wasted killing the pathogens in the gunk.
Make sure any new water is free of chlorine/ chloramine before it is added to the tank.

Clean the filter if it hasn't been done in the last 2 weeks. However, if the filter is less than 6 weeks old, do not clean it. Wash the filter materials/ media in a bucket of tank water and re-use the media. Tip the bucket of dirty water on the garden/ lawn. Cleaning the filter means less gunk and cleaner water with fewer pathogens so any medication (if needed) will work more effectively on the fish.

Increase surface turbulence/ aeration to maximise the dissolved oxygen in the water.

 

[Colin_T]

If you haven't already done so, you should contact the company you got the fish from and let them know what is going on. Send them pictures of the dead and sick fish.

 

[James_R]

When was the last time you did a water change on the main tank?
How often do you do water changes and how much do you change?
Do you gravel clean the substrate when you do a water change?

Do you dechlorinate the new water before adding it to the aquarium?
Do you have chlorine or chloramine in your water supply?

What sort of filter is on the aquarium?
How often and how do you clean the filter?

----------------------

This isn't caused by gill flukes. Gill flukes are small flatworms that live on the fish's gills and feed off their blood. Fish can live for months or years with gill flukes and only die from lack of blood if there are lots of flukes on their gills. The gill flukes can also cause scar tissue on the gills and this makes it harder for the fish to breath, but it takes more than 2 days to be an issue.

The Melanotaenia boesemani is covered in excess mucous (creamy white film over entire head, body & fins), which is produced by the fish when something in the water is stressing it out. This is normally water quality related (ammonia, nitrite or nitrate), or some sort of chemical in the water that is irritating the fish.
You need to test the water for ammonia, nitrite, nitrate and pH and post the results in numbers here.

The pink around the gills on the fish and slightly flared gills is normally caused by poor water quality (ammonia, nitrite, nitrate) or low oxygen levels in the water. This can happen when the fish are in the bag being transported to your house (for the Otocinclus) and the fish are in the bag for a long time or they weren't purged (withhold food) for 24 hours before packing.

The bloated cherry barb is probably dropsy and not a swim bladder issue.

If you post a video and pictures of the remaining fish it might provide more information. Upload videos to YouTube, then copy & paste the link here.
If you use a mobile phone to film the fish, hold the phone horizontally (landscape mode) so the footage fills the entire screen and doesn't have black bars on either end.

----------------------

BASIC FIRST AID FOR FISH
Test the water for ammonia, nitrite, nitrate and pH. Post results in numbers here.

Wipe the inside of the glass down with a clean fish sponge. This removes the biofilm on the glass and the biofilm will contain lots of harmful bacteria, fungus, protozoans and various other microscopic life forms.

Do a 75% water change and gravel clean the substrate every day for a week or until the problem is identified. The water changes and gravel cleaning will reduce the number of disease organisms in the water and provide a cleaner environment for the fish to recover in. It also removes a lot of the gunk and this means any medication can work on treating the fish instead of being wasted killing the pathogens in the gunk.
Make sure any new water is free of chlorine/ chloramine before it is added to the tank.

Clean the filter if it hasn't been done in the last 2 weeks. However, if the filter is less than 6 weeks old, do not clean it. Wash the filter materials/ media in a bucket of tank water and re-use the media. Tip the bucket of dirty water on the garden/ lawn. Cleaning the filter means less gunk and cleaner water with fewer pathogens so any medication (if needed) will work more effectively on the fish.

Increase surface turbulence/ aeration to maximise the dissolved oxygen in the water.

When was your last water change on the main tank?
I did a 50% water change today for both the quarantine (QT) tank and the main tank before adding PraziPro.

How often do you change water and how much?

• QT tank: 30% every 3-7 days
• Main tank: 40% every 1-2 weeks

Do you clean the substrate during water changes?
Yes, I siphon the surface of the sand about once a month during a water change.

Do you dechlorinate the new water before adding it?
Yes, I use Seachem Prime.

Does your water supply contain chlorine or chloramine?
Yes.

What filters do you use?

• QT tank: Aqueon Quietflow 20 with sponge media from the main tank's canister filter
• Main tank: 2 SunSun HW304A canister filters with sponge, cotton pads, and Seachem Matrix

How often do you clean the filters?
I clean one canister filter each month, alternating them, so each gets cleaned every two months.

---

Testing Results (API Test Kit):

Main tank:

• Ammonia: 0 ppm
• Nitrite: 0 ppm
• Nitrate: 15 ppm

QT tank:

• Ammonia: 0 ppm
• Nitrite: 0 ppm
• Nitrate: 5-10 ppm

---

Other actions taken:

• Wiped down the glass with a sponge after scraping off visible algae.
• Cleaned the canister filters today when removing the carbon for PraziPro.
• Will clean the QT tank's HOB filter shortly.
• Added air pumps for both tanks to increase surface agitation and oxygen levels.

---

Posting video and pictures:
I'll upload them tomorrow when the lights are on.

Update (now):
In the quarantine tank, one of the remaining four Rummy Nose Tetras seems to have recovered from the swim bladder issue it began to have earlier today. It's swimming normally and schooling with the others. I’ll monitor if it eats tomorrow. The fin rot has also stopped progressing, leaving only the ends of its tail fin frayed. The Emperor Tetras are still visibly healthy and alive. The otos are all alive.

I checked the main tank and found no additional fish losses. I counted all the fish, and the numbers match up, so no deaths since my last message. Both the fish in the quarantine and main tanks seem to be responding well to the PraziPro treatment. There are no visible signs of stress, like scratching or wall surfing.

I may have forgotten to mention earlier that the first five Rummynose Tetras that died appeared very skinny, with disproportionately large heads and gills compared to their bodies, similar to the rainbowfish that died in my main tank. - I will update tomorrow with a video.

 

[James_R]

QT tank starts at 4:02
Update:
I cleaned the HOB filter and pre-filter sponge in the quarantine (QT) tank about 20 minutes ago. The four Rummynose Tetras are now much more active and visibly healthy (they appear normal), including the one that showed signs of swim bladder issues yesterday. They're all eating and schooling together.

The only fish that died today was an Otocinclus from the main tank I found at the back.

I’m still uncertain whether I’m dealing with flukes based on your response, but if there are other parasites, the PraziPro should help eliminate them. Some of the fish that died so far were notably skinny when dead, which makes me suspect there could be internal issues.

 

[Colin_T]

The rummynose tetras look like a bad batch that just came in and haven't had a chance to recover from being transported from the fish farm. They have minor damage to the tail and are skinny (as you already noticed). Just feed them well and give them a month in quarantine before moving them. Same deal with the emperor tetras. They look to be in good shape but keep them quarantined for a month to recover.

The rainbowfish in the main display don't look too bad.

PraziPro contains Praziquantel, which is a deworming medication that kills gill flukes and tapeworms. It might also kill some external protozoan parasites but more research needs to be done in that area. Praziquantel should be used once a week for 3-4 weeks to kill any baby worms/ flukes that hatch after the first or second treatment. You should do a huge (75-90%) water change and complete gravel clean before re-treating the tank each week. Clean the filter each week before re-treating as well.

Most fish have thread/ round worms and you need Levamisole or Flubendazole to treat those.

 

[James_R]

Update:

There have been no deaths since Friday. The rummynose tetras are coloring up nicely, becoming more active, and are now eating well like the rest of the fish. The fish in my main tank are eating well and are doing well. However, all of the emperor tetras in my quarantine tank appear bloated. I was out since 4pm (they were normal then) and noticed this when I came back about 4 hours ago (9pm). At first, I thought they were pregnant. They ate the most compared to the other fish, and I feed them TetraMin flakes twice a day, giving only what they can finish in two minutes. I plan on giving them hikari brine shimp as a treat in a couple days (I do this weekly for all my fish). I was worried I might have overfed them, but I'm not sure since the rummynose tetras and the other fish in the quarantine tank, like my small platies, aren't bloated at all. The emperor tetras are still active, but I'm concerned it might be dropsy or internal worms. I'm not entirely sure. I've attached a yt video below:

 

[Colin_T]

It just looks like they have eaten a lot.

If fish get dropsy they don't eat, they just swell up and get really fat, much fatter than yours. Then they die.

With newly imported fish that are skinny, you should feed them 3-5 times a day and give them frozen food each day after they have eaten the dry food. This is especially important for skinny fish like the rummynose. Your main display tank can have frozen food each day too.

Do more water changes when feeding more so the tank water stays clean.
Make sure any new water is free of chlorine/ chloramine before you add it to the aquarium.