I need help for my girl! 27 year old Pacu

Steven's Pacu

Exodon
MFK Member
Sep 27, 2019
21
27
21
57
Fair Haven VT
Have you tested your water?
Yes
If yes, what is your ammonia?
.25 ppm
If yes, what is your nitrite?
0 ppm
If yes, what is your nitrate?
40 ppm
If I did not test my water...
...I recognize that I will likely be asked to do a test, and that water tests are critical for solving freshwater health problems.
Do you do water changes?
Yes
What percentage of water do you change?
31-40%
How frequently do you change your water?
Every month
If I do not change my water...
...I recognize that I will likely be recommended to do a water change, and water changes are critical for preventing future freshwater health problems.
Hello everyone, I've been following Monster Fish for a while now, and really need your expertise to help my Bonnie girl. She's a 27 year old, 3' Pacu, who was a gift for my son Steven's 5th birthday. I absolutely adore this girl, and can pet her like a dog! 🤗 A Big personality along with her size. Admittedly, I didn't know how big she was going to get, how long she'd live, and after 27 years of fishkeeping, I don't know nearly as much as I should. To be honest, I'm surprised she's still here. I know Pacus are hardy fish, but I've put this girl through the wringer. I have lot's of questions about filtration (especially particulates in the water), keeping a constant balance with nitrifying bacteria, and overall tank function and health, but firstly think she has ick. Some spots on her body, some scales missing from scratching I think. I've been dosing her 500 gallon tank with Melafix and Pimafix simultaneously for 3 days. The water is now more cloudy, her bottom lip looks more black and a little bigger than normal. I could be totally wrong, but my cloudy water usually means trouble with the nitrifying bacteria, and worried about oxygen with her swollen lips. I've added a space heater to her room to join her fluval heater.. Her spots are gone, but seems more agitated today. I can continue with both Pima and Melafix, but should I just ask my vet , or treat the tank with another brand of aquatic antibiotic? I know water quality is where this begins, and so need direction on how to balance this tank. It's so frustrating trying to figure it out. So many hours of research online over the years, and trying to understand how everything affects everything else. Temp, ph, nitrifying bacteria, ammonia, nitrites, nitrites, filtration, particulates, media, oxygen, sunlight, water hardness, Holy Hannah.. I am totally committed to making Bonnie's remaining years epic ones! I want to build her a much bigger tank so she can actually swim! She's currently in a 500 gallon bucket. Maybe for feeder fish? She has 2 fluval filters. One FX6, one FX4. The latter purchased a few months ago to improve oxygen levels in hopes of improving and balancing the tank bacteria. I'm just frustrated and want her to be well and happy. We lost my son Steven 8 years ago, and 'Bonnie the whale' is very important to us.. and friends that are totally amazed by her! My daughter used to read books to her. I'm sorry this is so long, but humbly asking for your help. I thank you in advance for any guidance you can give me, and thank you so much. 🙏🐳
 

Deadeye

POTM Curator
Staff member
MFK Member
Aug 31, 2020
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Welcome to the forum! Post pics of that pacu!

The first thing I’d do is increase water change amount/frequency. As a general rule, you don’t want nitrates going above 20, so at 40 ppm you will be seeing some issues.
 

fishdance

Redtail Catfish
MFK Member
Jan 30, 2007
1,788
952
150
If this fish is important to you, I suggest you call an aquarium maintenance company for a home visit as soon as possible. Things can go badly very fast for large fish in small tanks.
 

Steven's Pacu

Exodon
MFK Member
Sep 27, 2019
21
27
21
57
Fair Haven VT
Welcome to the forum! Post pics of that pacu!

The first thing I’d do is increase water change amount/frequency. As a general rule, you don’t want nitrates going above 20, so at 40 ppm you will be seeing some issues.
I absolutely will! I'll see if I can figure out photos to monster fish! Would you suggest every two weeks for water changes, or test more for an as needed guide? I'm always worried about losing nitrifying bacteria with too much siphoning, too many water changes or filter cleans. I always rinse media in existing tank water, keep it submerged, use Seachem prime for water changes, same water temperature. I've added nitrifying bacteria a handful of times after ammonia spiked, but it didn't seem to help. Actually the reverse a few times. Lots of factors to that maybe? Types of bacteria, water changes etc. So many questions, I'm sorry! 😅

If this fish is important to you, I suggest you call an aquarium maintenance company for a home visit as soon as possible. Things can go badly very fast for large fish in small tanks.
Hi there, and thank you for that. I live in a little town in Vermont, and Petco is the only expertise closest to us. All new hired hands, and not much education. I'll certainly try Burlington or NY way though. It's a great idea, but may be a reach. Here's hoping 🙏 It's so interesting that you said a small tank. I've always thought the tank was too small. Equivalent to us standing in a closet! Everywhere that I've read online, following inch of fish to gallons of water, says 500 gallons is sufficient. I have a friend who builds ponds, and has many carp outside, then inside. He's offered to help me build a bigger tank. Do you have thoughts on how many gallons would make her happy, but not too many, if that makes sense? 😃
 
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kzimmerman

Piranha
MFK Member
Mar 18, 2009
876
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delmar md
The one inch per gallon rule is a horrible rule to go by. A 2" fish has about 4 times the body mass of the same fish at 1" typically. Pacus are very massive for their length, they are just big bodied fish! The tank footprint is a much better indicator of tank size, I try to aim for twice the body length in depth and four times in length. Height isn't as important. Do you have plenty of surface agitation to aerate the water? What do you feed it? Do you have any pictures?
There is no "too many" gallons, the larger the tank, the better the fish will be.
You might want to think about an indoor pond. Probably the most cost effective way you can make a suitably large enclosure.
 

thebiggerthebetter

Senior Curator
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Dec 31, 2009
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Naples, FL, USA
Welcome to the MFK!

Congratulations on keeping your pacu for 27 years. It is quite a remarkable achievement!

Sounds like you know a lot but need a bit of guidance.

Most usually an illness results from stress. Must ID and eliminate the source of stress. If the illness is in the acute phase, must treat too but again should have at least a good guess at diagnosis, not treat blindly. Mela and Pima are mild antiseptics while, if the ich is the correct diagnosis, it is an external parasite. No logic here.

SP: cloudy water usually means trouble with the nitrifying bacteria,
TBTB: it does often when the system is cycling, yes, but in your case it could be simply the medication

SP: and worried about oxygen
TBTB: yes, mela and pima deplete oxygen, usually when people use these, they add aeration / stirring. half the peers don't believe mela and pima do anything, half thinks it does something.

SP: with her swollen lips.
TBTB: i dont see a link of the lips with oxygen

SP: Her spots are gone, but seems more agitated today.
TBTB: stress

SP: I can continue with both Pima and Melafix,
TBTB: diagnosis or a good guess first

SP: I know water quality is where this begins
TBTB: YES! good job.

SP: It's so frustrating trying to figure it out
TBTB: it doesn't have to be

SP: Temp, ph, nitrifying bacteria, ammonia, nitrites, nitrites, filtration, particulates, media, oxygen, sunlight, water hardness,
TBTB: temp is trivial, pH not important except MUST be stable, NH3 NO2 NO3 is basics, particulates are totally irrelevant except for your viewing pleasure, oxygen is critical but trivial, lighting is of 10th importance, water hardness is trivial

SP: I'll see if I can figure out photos
TBTB: button in the left bottom corner of the reply window says attach files

SP: Would you suggest every two weeks for water changes, or test more for an as needed guide?
TBTB: I'd suggest 50%+ daily until the fish is healthy and 50% weekly or more from there

SP: I'm always worried about losing nitrifying bacteria with too much siphoning, too many water changes
TBTB: these do not affect nitrifying bacteria, they live on surfaces, not in the water column, they live ON you filter media

SP: or filter cleans. I
TBTB: that is a valid worry, you dont want to clean out filter too often, nor too infrequent, now having two canister filters it should be a charm - do one at a time, stagger; most important thing with canister filters is that water entering them MUST be as aerated as possible in your tank, best if drawn from the surface, not from the bottom of a largely stagnant tank or from a dead spot, that'd be terrible

SP: I've added nitrifying bacteria a handful of times after ammonia spiked, but it didn't seem to help. Actually the reverse a few times. Lots of factors to that maybe? Types of bacteria, water changes etc.
TBTB: NBs need long time to settle and start growing, what you added were seeds, it takes time to grow and the right conditions, one of the most overlooked is the oxygen, NBs need oxygen, the more, the better they will work for you, which is why wet-dry, biowheel, shower type filters are in general 10x more efficient per volume of media vs canisters, HOB, barrel, bucket filters etc.

SP: the tank was too small. Equivalent to us standing in a closet!
TBTB: good thinking

SP: Everywhere that I've read online, following inch of fish to gallons of water,
TBTB: This is for guppies and bettas

SP: says 500 gallons is sufficient. I have a friend who builds ponds, and has many carp outside, then inside. He's offered to help me build a bigger tank. Do you have thoughts on how many gallons would make her happy, but not too many, if that makes sense?
TBTB: for large fish it is 1 cubic inch per gallon, so say you pacu is 36" long 18" tall and crudely on average 3" wide = 1944 cubic inches! = need 2000 gal of water. and this is minimum. More is better. I may be off by a factor of 2, maybe she is only 1000 cubic inches, it is still 2x more than what you have now. again minimum.. so for comfort double the minimum, come back to the same 2000 gal that's roughly a 12ft x 3ft round above ground pool, cheap too. even vinyl liner will suffice if no folds , no creases, otherwise she will bite them up and make million holes.

HTH.
 

thebiggerthebetter

Senior Curator
Staff member
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Dec 31, 2009
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Naples, FL, USA
... My daughter used to read books to her...
That's a first :O I'd hope they were Brazil aquatic documentaries... because Cat in a Hat and Alice in Wonderland would go way over Bonnie's head. I can't even wrap my head around them :)

pacu mom pacu mom Susan, helpful tips here :)

On a serious note, pacu IQ is scary high for a fish. That's true. And regrettably makes them one of the most horrible tank mates because they know how to take advantage of tank mates often injuring them or even killing them when eating their fins, barbels, anything that sticks out and fits in their mouth. The beauty of giving Bonnie 2000 gal of water at least is you can add some more tank mates but be careful how you choose them and ask us for an advice, the fish collectors who do keep large pacu will be able to advise you well.
 
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Deadeye

POTM Curator
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Aug 31, 2020
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I absolutely will! I'll see if I can figure out photos to monster fish! Would you suggest every two weeks for water changes, or test more for an as needed guide? I'm always worried about losing nitrifying bacteria with too much siphoning, too many water changes or filter cleans. I always rinse media in existing tank water, keep it submerged, use Seachem prime for water changes, same water temperature. I've added nitrifying bacteria a handful of times after ammonia spiked, but it didn't seem to help. Actually the reverse a few times. Lots of factors to that maybe? Types of bacteria, water changes etc. So many questions, I'm sorry! 😅
Increase in water changes doesn’t do anything to bacteria, but to great of a change in water params can shock the fish - best to take it slow at first and slowly ramp up the amount. That said - pacu are as tough as nails. Ideally, you’d be doing big and frequent enough water changes where the tank water basically matches that coming out of the tap.
thebiggerthebetter thebiggerthebetter explained that much better than me though.
 

jjohnwm

Sausage Finger Spam Slayer
MFK Member
Mar 29, 2019
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As usual, Viktor's practical approach makes good sense. The idea of using the inch-per-gallon "rule" with any fish much bigger than an inch is scary.

Just one point to mention here: this fish is, by any standards, a very senior animal. Like all seniors...people, dogs, cats, whatever...she is likely not as vital as she once was, with reduced immune response and generally not as resilient or quick to heal/bounce back from any stress or trauma. I wonder what the average maximum lifespan of a Pacu is in the wild. For that matter...I wonder if anyone knows.

I won't even hazard a guess as to the lifespan in captivity, because virtually nobody has the facilities, commitment or experience to keep such large fish. The vast majority of truly monster fish like this are purchased, owned and live out their unnaturally shortened lives in tanks their owners consider "big"...100, 200, 300 gallons...and die long before their time simply due to stress-induced disease when they grow large enough to overwhelm the carrying capacity of their tanks, or to overwhelm the water-change capacity of their owners.

You've learned a lot in 27 years and have done an amazing job of keeping this fish. You are likely more qualified to answer questions than most of us; you did a lot of things right to get to where you are now. As fish grow they sort of sneak up on you; that which has worked for years eventually becomes inadequate when the fish achieves a large enough size, but when you see and interact with the fish daily you become almost blind to its increasing biomass and it becomes easy to overlook it.

Fish are not immortal; even under perfect conditions, they live out their lives and eventually die. If you can keep any fish, and most especially a monster like this, long enough for it to pass away of natural causes..."old age"...you have nothing to apologize for...and the vast majority of aquarists will never achieve this.
 

Steven's Pacu

Exodon
MFK Member
Sep 27, 2019
21
27
21
57
Fair Haven VT
I've taken some photos to show tank set up, and aeration. I tried to upload a video but don't see it yet. I know you'll need better lighting and closer photos to see Bonnie's bod for health. 🤞🙏 My 4 year old granddaughter is here, so like the old calgon commercials for the next few hours. I can catch up on all the wonderful suggestions and respond soon. You guys are EPIC!!! 😃🥳🐳 Thank you so much for you time with this.

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