(210G - Please Help) Lethargy/Gasping

Hi everyone,

Please take a moment to read and help if you can. I feel like I might be dealing with a potential tank-wide issue and I'm worried for my cichlids.

I'm reaching out because I feel like I'm out of ideas on what's going on in my 210g tank. I have a South American Cichlid tank. The past couple days one of my Gold Severums has been acting pretty lethargic and breathing heavier than normal. He doesn't hide or stop moving, but he stays in his quiet area more often. He hasn't been begging for food at all and has only eaten a pellet at a time until tonight where he actually ate a few pellets. Now my Electric Blue Acara is avoiding eating tonight and she's mostly staying near her driftwood spot she's claimed.

I feel like something is going on. I had a power outage on Monday for about 4 hours and these problems began Tuesday. I suspected oxygen from that might have been a problem so I did a 50% water change last night. I have two airstones pumping bubbles that have been running since the power returned Monday, so I don't see how oxygen could be the problem. That being said, whenever I feed the tank, I notice all the fish start breathing a bit heavier/slow down and my pleco swims up to the corners of the tank (though I suppose this could be digestion). Still, I don't see how the oxygen could be low with a fresh water change and 2 airstones.

Next I looked at parameters in case my canister filters poisoned the tank due to the power outage. Zero ammonia, zero nitrite, 10 nitrate. pH is stable too. Nothing. Next I checked for illnesses on the affected fish, no signs of ich or any other redness/swelling, just heavy breathing, gills working hard, and lethargy. I checked the rest of the fish who are acting normal and didn't find anything wrong with them either.

Next I watched the tank for any bullying. I waited from afar when I knew they couldn't see me to observe their natural behavior. No bullying beyond the normal cichlid bluff charge every now and then.

To be honest with you, I'm at a loss here. For all I know nothing could be wrong and I may just be paying closer attention to some of my fish choosing to skip meals every now and then since my guard is up, but I truly don't know for sure. I read about the potential of gill flukes, but identifying it and treating it seems difficult. Please let me know if you have any ideas. I noticed a weird fungus growing on the inside of my canopy tonight from water exposure and for all I know maybe that's the problem... I cleaned that off.

Gill flukes are easy to treat with Praziquantel (Prazipro). The medication can be administered directly into the primary display tank. It does not adversely affect the aquarium environment. Safe for plants & scaleless fish.

Gill flukes are easy to treat with Praziquantel (Prazipro). The medication can be administered directly into the primary display tank. It does not adversely affect the aquarium environment. Safe for plants & scaleless fish.

Click to expand...

Thank you A201! Does this sound like flukes or something else? My only new additions were bala sharks about a month ago but they cleared quarantine without any issues... so strange.

Flukes are always present on fish. If for some reason the fish's immune system weakens, flukes can take over.

It won't hurt anything to dose Prazipro. It's not a bad idea to occasionally, preventatively dose it.

It’s tricky to identify the problem, but I don’t believe it has anything to do with the power cut. In 2024 we had a long severe drought which resulted in power rationing, we had sometimes up to 14 hours a day with no power (in 3 separate blocks) and very often 6-7 hours a day. This went on for several months. I have a 220 gallon South American cichlid tank and nearly all my fish in this (and my other) tanks were fine despite the lower temperatures and filters not working for long periods. I did lose my two Uarus, I think the low temperature probably weakened them, but this only happened after several months of power cuts. So I don’t think
one power cut of 4 hours could have any immediate effect, unless the tank was very overstocked. Anyway it won’t do any harm to do as A201 suggests in case this is the issue.

I believe you said the severums were spawning recently, what happened there, was there any unusual aggression that might have stressed the fish, compromising their immune system perhaps?

It’s tricky to identify the problem, but I don’t believe it has anything to do with the power cut. In 2024 we had a long severe drought which resulted in power rationing, we had sometimes up to 14 hours a day with no power (in 3 separate blocks) and very often 6-7 hours a day. This went on for several months. I have a 220 gallon South American cichlid tank and nearly all my fish in this (and my other) tanks were fine despite the lower temperatures and filters not working for long periods. I did lose my two Uarus, I think the low temperature probably weakened them, but this only happened after several months of power cuts. So I don’t think
one power cut of 4 hours could have any immediate effect, unless the tank was very overstocked. Anyway it won’t do any harm to do as A201 suggests in case this is the issue.

I believe you said the severums were spawning recently, what happened there, was there any unusual aggression that might have stressed the fish, compromising their immune system perhaps?

Click to expand...

You regulars are what makes this forum special! Thank you both for your help as usual. The breeding behavior hasn't returned since my post on that issue so no new spats or anything - unless my big male was injured during that and that's why he's acting this way... but it'd be weird to see the results of that fight showing up this long after. He is doing better today in terms of his movement but still breathing heavy.

It also wouldn't explain why my EBA is having seemingly the same issue. I did learn today that my airstones were possibly doing less for my tank than I thought they were. My FX6's have the outake positioned pretty low below the water line, so I angled them up a bit to hopefully provide more breakage and I might just get a wavemaker at this point too. I'm pretty stunned something called an "airstone" that shoots a billion bubbles doesn't do much for oxygenating my tank!

Your story about the power outage you experienced definitely makes me second guess my situation, but the timing of my power outage is too coincidental for me to write it off... I just have this feeling my FX6's weren't doing enough and the airstones weren't the solution I thought they were. A few months back we had company over and they accidentally flipped off my system for 8 hours trying to turn off the house lights. By the time I woke up I had gasping fish and a dead Tapajos school. I got the airstones after that catastrophe as a solution. Now months down the line, another 4 hour period of no power and suddenly I have some gasping & lethargic fish.

Is it possible my system has been perpetually running on low oxygen and the slightest downtime in equipment being off pushes it over the edge? If so I might have fixed it by positioning the filter outakes up to the surface. Either way I'm going to buy a wavemaker. (I'm also going to dose PraziPro per your earlier recommendations!)

What temperature's is your tank at?
Did you smell any “rotten egg” odor?
Yes to Prazi, but do follow up dosages/treatments to be sure to nail hatching eggs.
What perplexes me is that your other fish are “normal”. Have any of the affected fish flashed or rubbed against any surfaces? How are your Bala Sharks (new fish) doing and how long was the quarantine period?
Just trying to gather data.

It's nice to hear from you again bgarthe!

Tank is consistently 76 degrees.

No rotten egg smell of anything similar to it.

No flashing that I've seen from any fish in my time observing.

The balas were quarantined for 2 weeks. They haven't had any strange behavior since purchasing them and are still active & doing well.

What temperature's is your tank at?
Did you smell any “rotten egg” odor?
Yes to Prazi, but do follow up dosages/treatments to be sure to nail hatching eggs.
What perplexes me is that your other fish are “normal”. Have any of the affected fish flashed or rubbed against any surfaces? How are your Bala Sharks (new fish) doing and how long was the quarantine period?
Just trying to gather data.

Click to expand...

Your 76 degree temp all but rules out O2 deprivation as an issue as a 210g tank would surely have plenty unless you were improperly dosing CO2. The two week QT is the bare minimum, but at least you did that which is good. No flashing is also better to see.
Your increasing surface agitation is good. Treating with Prazi is good. Then wait and watch to see what happens.
Recently my Angelfish kinda just sat in the corner for no real reason and came out to eat and went back. After a few days, he was back to patrolling the tank. All the while, the rest of the fish were perfectly fine. Go figure.
Keep us updated plz.

One thing worth separating out: 76F does not rule out low oxygen. Saturation at 76 is about 8.4 mg/L against 8.0 at 82, so temperature is a small lever next to how much a stocked 210 consumes and how fast the surface renews it. You found the bigger variable yourself when you noticed both FX6 returns were sitting well below the waterline.
The fungus in the canopy points the same way. It grows because that air space is humid and undisturbed, and gas exchange happens against the air actually sitting on the water. Airstones mostly buy you surface movement rather than transfer from the bubbles themselves, so angling the returns up was probably worth more than both stones.
Cheap test before you medicate further: count gill beats at lights-on and again late afternoon, same fish. Oxygen bottoms out at dawn after a night of respiration with no plants photosynthesising. Worse in the morning and easier by evening points at gas exchange. Flat all day points at the gills themselves, which is where flukes would put it.
One caution on the Prazi: it pulls dissolved oxygen down while it works, so keep the surface moving hard through the treatment.

One thing worth separating out: 76F does not rule out low oxygen. Saturation at 76 is about 8.4 mg/L against 8.0 at 82, so temperature is a small lever next to how much a stocked 210 consumes and how fast the surface renews it. You found the bigger variable yourself when you noticed both FX6 returns were sitting well below the waterline.
The fungus in the canopy points the same way. It grows because that air space is humid and undisturbed, and gas exchange happens against the air actually sitting on the water. Airstones mostly buy you surface movement rather than transfer from the bubbles themselves, so angling the returns up was probably worth more than both stones.
Cheap test before you medicate further: count gill beats at lights-on and again late afternoon, same fish. Oxygen bottoms out at dawn after a night of respiration with no plants photosynthesising. Worse in the morning and easier by evening points at gas exchange. Flat all day points at the gills themselves, which is where flukes would put it.
One caution on the Prazi: it pulls dissolved oxygen down while it works, so keep the surface moving hard through the treatment.

Click to expand...

Thank you for this great insight! I will pay attention to that for sure, but your point about oxygen being lowest at dawn makes me even more suspicious.

Whenever I get up in the morning (the tank lights are on by now) my fish are their most sluggish and it lasts through the afternoon. They start to perk up by the late afternoon/early evening. I attributed it to them being "tired" or "waking up for the day" but your analysis makes me think perhaps that wasn't the case at all.

I'll pay attention to their gill beats to look into this further but it's crazy how familiar your explanation sounds to my situation. I added a wavemaker last night as well which should hopefully be a big help too.

If you choose to use Prazipro, it's best not to use a sulphur based water conditioner such as Prime.
The sulphur has a neutralizing effect on the Praziquantel.

I use API Stress Coat, but there are many other brands of sulphur free water conditioners available.

Can you remind us how many fish are in this tank and what size they are please?

Can you remind us how many fish are in this tank and what size they are please?

Click to expand...

Hello,

Just as a general update for everyone, the Gold Severum ate pretty aggressively yesterday, he seems to be doing better! My Blue Acara is still in pretty rough shape though...

Regarding your question TClare -

1x Oscar (~6 inches)
5x Severums (3 of them are about 4 inches, 2 of them about 6 inches)
1x Blood Parrot (~6 inches)
2x Bala Sharks (1 is about 5 inches, the other about 7)
6x Silver Dollars (~4 inches each)
1x Blue Acara (~5 inches)
1x BN Pleco (~5 inches)

That is a lot of quite large fish for 210 gallons, so maybe it was due to oxygen shortage, my tanks are not that heavily stocked.

Perhaps the surface agitation wasn't enough for how stocked it is then? Parameters-wise the tank's about as clean as it can possibly be so I haven't really noticed any other symptoms of overstocking issues.

Longterm I will be rehoming the Silver Dollars. Their skittish nature hasn't been as fun to watch for how much space they take up.

I'm just wondering how I'd be able to deal with the peacock/hap tank I plan to do in my basement where they will be even more overstocked lol. Going to get an army of wavemarkers/powerheads.

I'll definitely continue to update how the Blue Acara is doing because the added surface agitation hasn't seemed to help with her issue.

Yes on the agitation, but with a correction on what capacity means: a tank's oxygen budget is surface area and how fast that surface gets renewed, not gallons. And the airstones were never doing the work you thought. The bubbles themselves transfer very little; they earn their keep by dragging water up to the surface. Angling both FX6 returns up did more for you than the stones did.
The part that does not fit a pure oxygen story is which fish got hit. The balas and the silver dollars are the highest-demand fish in there and they came through fine, while the two that did not are a severum and an acara, both of which hold station in the quietest corner of the tank. So low oxygen set it up, but the acara probably has a second problem stacked on top: gills irritated during the episode, which heals over weeks rather than days, or flukes, which is what the Prazi covers.
One change that costs nothing: move the main feed to late afternoon. Digestion raises oxygen demand for hours afterwards, and a morning feed lands that demand right on the tank's daily low.

Hi everyone,

Sorry I forgot to update, but everybody seems to have recovered well! I don't know what the cause ended up being but everybody is healthy again. Thanks all!

Hi everyone,

Unfortunately, I think I need to bring this back up again. My fiance accidentally fed the tank after I did on Friday, ever since my blood parrot has been sitting on the substrate breathing heavy. I've been feeding the tank every 2 days as a result, did a water change, and have been measuring the parameters - all parameters look good.

Still, the blood parrot hasn't moved much at all since Friday, only forcing herself around to try and eat.

Now, my OTHER gold severum from this tank is also sitting at the substrate breathing heavy as of today.

I do not know what to do. I have a powerhead going for oxygen. This tank is just constant issues and it's becoming more stress than it's worth. Please let me know if you have any ideas.

The feed may be a coincidence. In August it was the severum and the acara; now it's the parrot and the other severum. Same group of fish both times, and there was no double feed the first time. The balas and silver dollars have come through both.

Five days is also long for a feeding accident. Ammonia off one extra meal would have spiked and cleared by now, which fits your tests reading clean.

What came of the Prazi course back then, did the acara recover fully?