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FAQs on the Piranhas Systems

Related Articles: Piranhas, Serrasalmine Fishes, Characoids/Tetras & Relatives Feeding Feeder Goldfish,

Related FAQs:  Piranhas 1, Piranhas 2, & FAQs on: Piranha Identification, Piranha Behavior, Piranha Compatibility, Piranha Selection, Piranha Feeding, Piranha Health, Piranha Reproduction, & Piranhas and Relatives, Feeding "Feeder" Goldfish, Pacus, Silver Dollars,


Marine to Bathwater Conversion.. for FW, Piranha!        10/26/17
Howzit from South Africa,
<Right backatcha Gar; from S. Cal.!>
After a spot of research on keeping piranha I came across your site, 'bonus'! and thought I'd get your opinion/advice on my future plans.. I currently run a 1'000ltr marine system complete with all it's bits n bobs,
and a 400ltr sump, but unfortunately can't keep up with the maintenance regimen or associated costs. My thoughts are these;
Dump the salt water after removing the inmates and surviving corals Rinse/wash off the existing live rock mainly with the purpose of re-scaping the tank
Fill the tank with tapwater and treat with stabilizers etc.
Allow to cycle for 3-4 weeks
Add a clean-up crew (Pleco, fresh water shrimp, crab, snails etc.)
Considering adding a few black mollies to the sump for future feeding requirement
Add a few plants, and then the piranha.
With this game plan in mind a few assumptions had to be made; The live rock can be re-used in the tropical tank
<I'd switch this and the sand substrate as these are highly likely carbonate based, and will add too much to alkalinity and elevated pH here to be healthful for the livestock you list>
After cleaning the sand substrate in the dt that'll be good to go <Again, I'd sell or store, and replace this with something less reactive.
See WWM re freshwater substrate selection>
The current circulation pump and skimmer will suffice
<Yes; likely so>
I can remove the dsb(deep sand bed) and broken coral chamber in the sump
<Yes I would>
I can remove the 2x chillers and the water should be around 24C- 26C at most
(I'm assuming tropical/piranha are not as dependant on stable temperature as marines)
<They can tolerate a much wider range and fluctuation by and large>
I've been told I can lose the sump, skimmer, and circulation pump, and just put a submerged filter system in my existing Durso chamber, where I could also add a heater or 2 for winter.
<Good ideas; but I'd keep the sump and circulation pump... and likely use or have as back up. The skimmer can go into storage>
So that's about that then, it would be greatly appreciated if you could offer comment and assistance on my master plan.
Kind Regards
<Thank you for sharing. Please do send along pix, further observations as your project goes forward. Bob Fenner>

Tank agrade      5/26/15
I have an community tank of convict cicklids (sp?) That I'm going to be moving to a larger tank.... I remember keeping piranhas as a child the tank I have now 30 gallons is it possible to keeping them in this size tank?
<Ah no... try using WWM.
Bob Fenner>

Re: Pregnant Platy... now Piranha...  ala Neale the bartender  9/3/11
Hi Neal, sorry to bother you again but this is as urgent as things are going to get.
<Seemingly so.>
I went to the pet store to get cichlid pellets as a dietary supplement and I seen a rather disturbing image. the pet shop owner was going to put clove oil in a 90 gallon with a fully grown red belly piranha! '¦.
<Yikes! Why?>
I didn't want her to do this so I bought the only tank she had, a 15, for it. now trust me this is temporary. the fish is too big for that tank. so I asked to order a 25 gallon for me. it will be about a week and a half though before I get it. I call her Sarah, and she is fully grown. she is also 2 1/2 years old. she threw a fit when I put her in the tank but I know they stress easy.
she hasn't moved much, but I don't blame her its very well filtered as I got another oversized filter like the one I mentioned earlier. I've always wanted a red belly but this is too sudden. but there is no way I'm letting this beautiful fish die. so what I wanted to know was if she would make it? 15 gallons is not humane for her at all, but with a 25 on the way I hope she holds out. what should I do to make her more comfortable?
<Daily water changes, 25% or more, but keep temperature and water chemistry constant. Don't feed her; she doesn't need food right now. Keep the lights down/off. Keep your hands away from her, she might bite!>
there isn't much room for anything with her in there! so providing cover wont be possible without taking from the pathetic tank size. what would be the best thing to do? wait it out and keep stress down? I paid 250 for her'¦.
<250 US dollars?><<For a fish the store was going to destroy? Something fishy here. B>>
id give her to a good home but no one around here has a big tank for just one red belly.... I asked around and will continue to do so.... but if I cant find a home will a 25 gallon cut it? - Matt
<No, 25 gallons won't work in the long term. Contact a city or state fish club if you can. Alternatively, there is a forum called Monster Fishkeepers that's a place where big and predatory fish folks hang out. There may be someone there who can help you. Good luck, Neale.>
Re: Pregnant Platy   9/3/11
Yeah $250 Canadian. I'm kinda broke.
<I bet.>
temp at constant 75. I don't have a ph tester or anything of the sort. she was going to be put down because no one around here wants her and she taking up room in the store. I feel for this fish Neal, if I cant find anyone at all, what size is a minimum? I swear ill get it, I don't care because she deserves all the compassion I can give her.
<I guess a singleton could be maintained in 55 gallons; not ideal, but doable with a decent filter and regular water changes.>
the smaller the tank the better because I don't have much for money but she has to be comfortable. yes the lights are off. blinds down on my window to keep things as dim as possible. I did not feed her but tomorrow I will have to. I don't have any foods she can have at my disposal so table food will have to do. veggies I mean. being omnivores and eating fruit in the wild she will probably be okay with it.
<Don't feed her for the first week. Let her settle in. Piranhas aren't difficult to feed, but they do appreciate variety. Earthworms are a good, cheap first food. White fish fillet like tilapia and Pollack are cheap fresh or frozen foods. The odd prawn or mussel will be taken as well. Don't bother with live feeders -- they're risky, and don't provide any benefits.>
I'm only experienced with small fish... I may have to contact my 'father' who I haven't spoke to in some time.... I know he would take her but he is a jerk and will probably think she is a freak show.
<I feel for you.>
that would be a last resort. I have to laugh though because boy is she keeping an eye on me! my hands are staying far far away from her reach hahaha.
<Do, please, solicit help if you need it. There are surely Canadian fish clubs, and I dare say even zoos, public aquaria, animal rescue places that might offer help if you explain to them what you've said to me.>
but what should I do?
<Go slow, be patient; read about Piranhas:
Cheers, Neale.>
Re: Pregnant Platy... Piranha   9/4/11

ok... you have been so kind. my dad got home and freaked that I got a fish with such a bad media reputation.
<Yes, it's a reputation. Piranhas are really quite shy and nervous fish, especially in small aquaria. They aren't the cold-blooded killers they're often supposed to be.>
but I explained and I'm now sitting with him and planning a stand for a 60 gallon. ill get another filter of the same sort. also another heater at the other end to keep consistency. ill call the African wild safari. we have
about a 4 hours drive if they take her.
<Cool. But also try fish clubs; look for example here:
last time I was there I didn't see any fish exhibits though. the only thing in any water there were cichlids and a rather neurotic polar bear. thank you so much for all your help. I really mean it. I want to do what's best
for her.
<Glad to help, listen. I wish you luck for your kind act(s). Cheers, Neale.>
Piranha  9/4/11

Hi Neal, the Toronto zoo is going to take the piranha. someone will be out first thing in the morning to pick her up.
<That's real good news.>
my mom freaked when she seen it. but I told her and she was fine about it.
I'm glad I saved her though. she will have the perfect care for the rest of her life.
<All's well that ends well. Shame you're out of pocket; but will you get some passes to the zoo to come visit your fish? That'd be nice.>
but with this tank being empty...... I must fill it. I have had moderate success with fresh water. I want to try my hand at marine setups. if I got a small species of clown fish that will be all I would want in it. just one. how would I go about setting it up? this is of course theoretical.
but id like to try it. I'm not sure how though. any more advise left in ya?
lol many thanks, - Matt
<Marines aren't easy and they're also expensive, so buy or borrow a good book first. Bob F., the owner of this site, has written a very well regarded primer on marine fishkeeping called "Conscientious Aquarist" and I'd suggest that'd be an excellent first read. It covers setting up different types of tanks, what sort of budget and expensive hardware options work well, and then has lots of chapters on each different kind of fish and invertebrate. I have no hesitation recommending this book, and would do so even if Bob wasn't a friend. In the meantime, I would suggest you have a read of this article:
Bob suggests any tank smaller than 40 gallons is a "small" marine aquarium and consequently more difficult to set-up and maintain. I'd not disagree with that, but I will say that beginners can have success with small tanks, provided they go slowly and take care not to overstock. Live rock, a few shrimps, and perhaps a pair of farmed Clownfish (which don't need anemones!) would work rather well. Corals require very good water quality and (mostly) bright light, and that makes them much harder to keep, though some, particularly the polyps, are do-able if beginners make the investments necessary. Cheers, Neale.>
Re: Piranha... now back to stkg. sm. FW   9/4/11
Hi Neal, no I didn't get anything out of the ordeal other than the satisfaction that I did what's right for the fish. SO, I think ill leave a marine tank for later in life... I'm not as knowledgeable as id like to be about fish keeping. I'm excellent with the species aspect of it. but I guess ill keep this little thing a freshwater lol. what would be your favourite freshwater fish for a small tank? they must like a strong current too. I am
just going to settle down, re-evaluate finances and see what I can do. thanks Neal, - Matt
<All depends on the size of the tank. In something 8-10 gallons, Tanganyikan Shell Dwellers (like Neolamprologus brevis) are hard to beat for both personality and novelty. They cohabit with Enders Guppies, so with a bit of careful planning you can end up with a tank that not only looks pretty but may produce two different species of sellable fish! Some of the less widely traded livebearers can also be well worth keeping, for example a personal favourite, Limia nigrofasciata, a species with nice colours and
males that sport both a humped back and a Molly-like Sailfin. Banjo Catfish are another underrated group, as are Whiptail Catfish. If you have unusually strong water current, i.e., turnover rates 8-10 times the volume of the tank, then there are various "Hillstream fish" that might be tried, including the distinctly oddball Pseudogastromyzon cheni, which would get along nicely with White Cloud Mountain Minnows. Any of these float your boat? Cheers, Neale.>
Re: Piranha  9/4/11
lol yes thanks, its a matter of finding some of these though :) Thank you so much for everything Neal, you have been more help to me than anyone else. - Matt
<Always glad to help. Do consider joining our forum...
'¦which you'll find is a great place to chat with other fishkeepers and share experiences. Among other things, you can ask around for where people find and buy their fish. My perspective in the south of England isn't terribly useful for folks in the US, Canada or any of the dozens of other countries where people keep tropical fish. In the meantime, good luck! Neale.>
Re: Piranha   9/5/11

I will be sure to join! thanks again!
<Most welcome. Cheers, Neale.>

what size bulkheads holes should I drill into my tank and is a Quite One 5000 with 1330 gph overkill for 1 Black Piranha  9/12/10
Hello , I have a 75 gal aquarium that I am setting up to keep (a) Black Piranha in .
<Serrasalmus rhombeus. A potentially very large, and certainly very aggressive, if neurotically shy, piranha.>
Here is where I'm confused , I have read that piranhas need lots of circulation ( water turnover )
<Up to a point, yes. But you don't need to go bananas. Piranhas come from rivers and lakes, and they enjoy steady rather than turbulent water currents. One or two large canister filters (or possibly hang-on-the-back filters) should do the trick just fine.>
so I bought a Quite One 5000 , it pushes 1330 gph at zero ft. , now the guy from eBay where I bought the sump from said it holds 25 gal of water and from where the bulkhead holes will be drilled to the bottom of the sump
is roughly 30 inches . I plan on drilling 2 holes ,what size holes do you think I need to drill in the back top of the tank for the Quite One 5000 . I'll also have to drill 2 holes into the top of the sump lid , there is a hole there but its really small . ,,, Thank You ,,,
<If you intend to use a sump -- and it's a good idea -- then you need to go along to the marine section and read the articles there. Things like pipe sizes are discussed there.
The one key difference is this. Unlike a marine tank where you need lots of water currents at different angles, most freshwater fish are used to a single strong current, e.g., the flow of a river. All you want is a steady flow, preferably along the bottom as well as the top of the tank, such that a piece of flake food released at the bottom of the tank doesn't sit there but gets whooshed along. One or two outlets at the left hand end of the tank for the water to flow into the sump, and one or two outlets at the right hand end of the tank for the water return, will work nicely. Cheers, Neale.> 

Re: Piranhas, sys.   4/7/10
Neale, thank you so much for your timely response.
Any time I have asked a question to a so called on-line expert, I never received a response.
After browsing around your website I could see that you and your crew really are experts and I hoped for some response and what I got was more than I expected, so thank you!
<We're happy to help.>
The book that I read about piranhas is 'Piranhas' by Barron's I believe.
<Quite a good book, but dated.>
I really don't remember off hand exactly what tank size they recommend, but I was sure that 40 gallons would be enough.
<For a single specimen of a medium-sized solitary species perhaps, like Pygopristis denticulata, a species that gets to about 20 cm/8 inches in length. But some of the larger species are twice that size, and the gregarious species need something upwards of 75 litres/20 gallons per specimen, with a group of six being the minimum reliable group size. I wrote an article for Tropical Fish Finder that you might find useful; it's about the species on sale at one particular store in England, but the gist of the thing should hold true for species available in the US as well:
There are lots of myths associated with the piranha family, particularly those to do with diet. All piranha family fish eat some meat and some fruit, what varies is the bias one way or another. The more carnivorous piranhas eat fruit and seeds only seasonally, and mostly eat animals and carrion, while Pacu eat mostly fruit and seeds, but will take fish and other prey when the opportunity presents itself. You'd be surprised how many messages we've received from people surprised their Pacu has started to attack its tankmates!>
However, I take your word over theirs any day and I have purchased an 80 gallon tank. Thank you for the advice. -Tracy
<Sounds a good size tank, and should allow you to have some decorating the tank with bogwood, floating plants and some tall Vallisneria around the edges. I've seen some stunning planted piranhas tanks over the years, but
one of the funniest had a plastic teaching skeleton submerged in it!
Cheers, Neale.>

Piranha anyone?  Sel., sys.    3/18/10
A few weeks ago I tore down my African cichlid tank (found a new home for them all) since I had decided to take on the challenge of having Piranhas.
<Challenge is certainly the word. These are quite difficult fish to keep well.>
I find these are exciting and beautiful fish to have and legal in the state of Maryland.
<Honestly, I think a lot of people find the concept of Piranhas rather more exciting than the actual fish. Let's be clear about what these fish are like. Most days, they sit around doing nothing. They are extremely nervous fish and never really become "tame" in any meaningful way. At best, they're merely scared rather than terrified. They're crepuscular fish, meaning they're really only active during dusk and dawn, and won't to anything much when the lights are on unless there's plenty of shade (e.g., Indian Fern).
Feeding them isn't difficult, though the whole live food aspect is overdone and misunderstood. Setting aside the thrill teenage boys get from throwing live Goldfish (or worse, mice!) into the tank, Piranhas are correctly maintained on fresh or frozen foods, never cheap feeder fish. They don't need daily feeding, so half the days of the week these fish do precisely nothing, unless of course you prefer to feed smaller quantities daily. Like all carnivores, avoidance of Thiaminase creates problems if you don't research food items carefully and balance those foods that contain Thiaminase (like prawns) against a greater quantity of foods that don't (like tilapia fillet). Very few species are gregarious *once mature* and even the social Pygocentrus spp. are temperamental in this regard, and more often than not aquarist buy a group but end up with a singleton. Since it's really a gregarious fish, being kept in solitary means it is EVEN more frightened than the average Piranha. For a group of six Red-bellied Piranhas -- the minimum number for which you have a better than 50% chance of a stable grouping without serious fighting/death -- you need not less than 450 litres (about 120 US gallons). Filtration needs to be top-notch since all Piranhas expect high oxygen content and zero ammonia/nitrite levels. While not precisely delicate fish, there is some variation among species in terms of things like tolerance for copper, so mortality can be high if you don't know precisely what you're doing. In short, apart from their reputation, these fish have almost nothing going for them as pets. By
every objective measurement they're poor choices for the home aquarium.>
My tank is 90 gallons and has 2'' ferrite soil with a gravel top, various live plants, and three awesome bogwood logs that look like they just came straight out of the Amazon. Two Fluval 405's and two Whisper EX70 hang-on
power filters, of which one is currently employed, and a Koralia 4 power head to keep the water flowing through and around the bogwood. The LFS received a large shipment of juvenile (2") red bellied Piranha (P. nattereri).
<Very small specimens, paradoxically, are often the most vicious towards each other outside of spawning adults, even though wild piranhas are gregarious. So watch them carefully, and look for signs of biting, missing eyes, etc. When setting up a group, the best size to go with is the subadult, around 10 cm/4 inches. That's about the size of Silver Dollar fish.>
My question is how many can I stock (I'm thinking 5)
<Not enough. Five Red-bellied Piranhas = One dominant Piranha, and four dead Piranhas.>
in my tank based on the current set-up? I have done a lot of research on OPEFE since Bob mentioned them in one of his postings, and that is a great site for learning about this species. I don't want to get too many and I don't want to get to few of them either.
<You need at least 6, realistically 8 or more, for a stable group.>
I do have moderate lighting for the plants but there is also a lot of "shade" from the bogwood logs,
<They don't use logs. Must be floating plants. The shade MUST be above them, not on the ground. These are midwater characins, not catfish.>
would this be ok or do I have to lesson it a bit (160 watts)? Also, can you have an algae cleaner in there or will it upset them?
<Look, you're lucky if they don't bite you when you're cleaning the tank.
Seriously. Happens all the time. Think a catfish is going to work...?
My tank has been up and running now for a few weeks without fish.
<Look instead at Exodon paradoxus, a far more active, and far smaller, schooling characin that has better colours but the same "feeding frenzy" behaviour. In your tank you could keep 20 specimens without problems.
They're fantastic fish, and will go into their feeding frenzy every day just for flake food, let alone tidbits of fish fillet or bloodworms. I don't mean to squash your hopes, but Piranhas really aren't good pets, and you can quickly end up with a big, expensive tank filled with boring fish.
Cheers, Neale.>

Piranhas and Pacu (Oh! MY) Robert: <Anthony Calfo in your service... Bob has superglued himself to a piece of coral...strike one on his first foray into coral propagation> Thought I would give you an update and ask you a few more questions, if you don't mind. It's been over 6 weeks since I've had the tank set up and the Piranhas are doing fine - despite the fact that I have yet to get the pH down to their ideal range: 6.5 - 7.0 The tank has reverse osmosis water in it so it's very soft (85 ppm) so I would think that the pH would adjust fairly easily, yet it won't go below 7.6!  <what is the total hardness of the water coming out of the R/O unit and has this number been confirmed with another brand of test kit?> It's a mystery to me why the pH won't budge.  <85ppm is soft...but not extremely soft assuming that the test kit is accurate and not reading a bit low (which could explain the resistance)> The tank has been up for a while now and according to what I've read, all established tanks will see a decrease in the pH levels as this is a natural process.  <agreed and inevitable for most> I've also read that the softer the water, the less buffering and therefore the easier it is to adjust pH levels.  <yes> Maybe 6 weeks isn't long enough and maybe 85 ppm is still too hard of water. Any ideas on what's going on? <you are correct on both counts...but don't be obsessed with the low pH and soft water unless you are trying to breed them. The other side of the coin is that very soft and very acidic water is VERY unstable and quite frankly dangerous with the slightest slip in husbandry (overfeeding, delayed water change, etc)> I'm going to be setting up an 125 gallon soon and will have a Pacu in that tank.  <the tank is still not big enough...quite frankly, I hope that you don't buy the fish. It's an inappropriate animal for most tanks growing to over two feet in length. Cruel to let it stunt and die prematurely (a few years old) as most do> My research indicates they like the pH levels even lower: 4.8 - 6.5! <too dangerous for captive aquariology unless you are research strict about maintenance> If I can't even get my 55 gallon to a neutral pH...how am I possibly going to get an 125 gallon to a pH level of 4.8 - 6.5 ??? <my friend, have you considered drinking alcohol? Relax, goombah. A pH around neutral is safe and reasonable for such hardy fish and will serve you well considering the waste load they produce and potential for disaster at low pH/unstable soft water. If you are willing to go to such great lengths for water quality... breed wild caught discus instead and at least make money for your pains...hehe. Kindly, Anthony> Travis  

Follow-up to Piranhas and Pacus Oh My! Anthony: <You got Steven pulling his shift answering some of the daily mail.> Thanks for your input...I appreciate it! Can you tell I'm just a tad on the obsessive compulsive side? he he I'm glad to hear that I don't need to be so worried about the pH levels and can relax a little. I do have a couple follow up questions on the Pacu. Don't these fish grow to the size of the tank? From what you're telling me they'll just grow and grow and grow until they basically die (if the tank is too small). <It is not quite true that fish grow to the size of their tanks. Freshwater fish are a little easier to stunt their growth, but that is not healthy at all. How would you like to live your whole life in your closet? Get the picture.> How big of a tank do you need for a Pacu? <For any large fish, find the maximum length. The tank's width should be twice the maximum length of the fish and the tank's length should be four times the maximum length of the fish. And remember that this is a minimum. For a Pacu, 4 foot wide and 8 foot long and probably 2 or more feet deep.> I'm not necessarily "married" to the idea of getting one so I'm open to alternatives. Can you think of any? The Pacu is the exact kind of fish I'm looking for: a freshwater fish, grows very fast, grows very big and won't attack you if you put your arm in the tank! I've tried Oscars in the past but had terrible luck with them as they always got some kind of disease (ich, hole-in-the-head, etc.). I can't think of any fast growing, large freshwater fish other than Pacus and Oscars so that's why I thought I would consider a Pacu. Any suggestions? Travis <Generally, Oscars are a great fish as long as you keep their water clean with frequent, large water changes and good filtration, house them in an appropriate sized tank, and feed them a varied diet (no feeder fish). There are many other cichlids that meet you request, but they all have the same captive care requirements as above. Kind regards, Steven Pro>

Red (-Bellied) Piranha Hi there! I have 3 Red (-Bellied) Piranha, but they are all stressed. Every time I go near the tank, they all swim around and hit on the glasses. Even I feed them, I have to go away from the tank, otherwise they won't eat. why do they like that? Is there anything that I can recover them? Thank you <A few things would likely help here... providing more cover in the way of plants and driftwood... more circulation in conjunction with your filtration, and inclusion of some "dither fishes"... like other characiform fishes and South American catfishes... as well as time going by, the tank being in a more public thoroughfare area. Bob Fenner, who says, we placed our Piranha piece's images last week on the www.WetWebMedia.com site, and took a few more pix yesterday at the Steinhart Aquarium... now need to flesh out the text for article and more inclusion>

Enough Oxygen in Piranha Tank? I have a 120 gallon "high" tank (22-24" high and 5' long). I have 5 Piranhas in the tank and the water is set at 79 degrees. I use 2 AquaClear 500 filters and a Magnum 350 canister for continuous polishing. I also have a Hagen Powerhead (model 900 something) that turns about 400 gallons per hour. I use the power head for current only. I have the power head on a timer. It's on for 30 minutes, off for an hour, on for 30 minutes, off for an hour, etc. for each day. I know it's harder to get good oxygen in warm water <Correct, but 79 is not too hot, just about right.> just want to be sure my fish are getting enough oxygen. And how can you tell if you're not...do the fish become lethargic or something? <Yes, become lethargic, stay at surface gasping for air.> 2 of my Piranhas always stay about 1/2" from the top of the tank in the corner while the other 3 stay at the very bottom. Not sure if this is due to oxygen levels or not. Any ideas? Travis <Could be territorial disputes. Oxygen levels can be verified by test kits. Also, look at the other regular parameters; pH, ammonia, nitrite, & nitrate. -Steven Pro>

Piranhas in a 55gal. hello, I have a 55gal. tank and have two 2.5inch piranhas and want to add more. I was wandering how many I could add if any, and if I should take the two piranha I have now out and put them back in with the new ones. what do you think? john <I really like this group of fishes (a subfamily or family of what we generally call tetras or characiform fishes, the Serrasalminae or Serrasalmidae), but in order to give you more of a definite answer I need to know the species we're talking about. Please read here: http://www.wetwebmedia.com/FWSubWebIndex/serrasalminae1.htm As you can see some Piranhas get quite large, and some species are much more difficult to keep together in such a small volume as yours... The time to add any is when they're small for sure, and all the same species, about the same size... Bob Fenner, who wishes these fishes weren't outlawed in California.>

Crowded Piranhas When baby piranha starting getting bigger and older; I have the tank well planted and plenty of hiding spots for the fish. Now the Piranha are developing the Red characteristics, should I remove these hiding spots? The rock takes up a lot of room and it used to house 4 piranhas, now it could probably do 1 or 2; I am worried about the fish fighting with each other, what should I do? <<I don't know the size of your tank but I'm guessing it's fairly small. The safest course of action would be to get down to 1 or *maybe* 2 fish. Ronni>>

Red belly piranha I have a red belly piranha. I have had him for about 3 weeks he is about 3 1/2 -  4 inches. I came home and he was sitting sideways looking at the top of the tank like he was dead but when I touched the plant he was moving again what is the problem  <Hi there. Red Belly Piranha are pretty messy fish, and they quickly foul water unless you give them a large tank with plenty of filtration. They are used to living in a river system with constant fresh water flowing. I would test the water levels and make sure that the ammonia and nitrite levels are okay. Then add powerhead to increase current, also airstone and air pump to add the needed oxygen. I also suggest you check out websites like www.piranhafury.com, there are many piranha owners there that can help you enjoy your pointy toothed little fish. good luck. -Magnus>

Piranha Systems Hi, I have recently bought some piranhas, they are all about 2-4 cm and I think they are red-bellies (they are silver with black spots and red bottom fins). <Likely this species or Pygocentrus piraya> I read questions on your site and just wanted to know if my conditions are ok and what to do to improve the health of my fish (having read the lack of understanding many people have of them I am keen to get it right and be able to take full care of my fish). For a start I have a 62 litre tank (is that about 16 gallons?) with 6 piranha of the size I said. <Yikes... this is a way too small volume for this number of fish... even when small you will find them chewing each other up substantially... eventually killing all but one... This number of piranha really should ultimately be kept in a system about ten times this size> I'm feeding them frozen bloodworm and brine shrimp, lately I have been feeding them more than the shop owner's recommended half a cube a day because they bite each others' fins.  I have lots of real and fake plants in the tank, as well as some fake tree roots ( I read they like lots of cover)... <Yes> ...and a skeleton that bubbles. I have a heater at 77*F and filter (I say simply filter because I don't quite understand biological and mechanical filter and all that)... <Oh, simple to grasp...> ...it is one that sits in the tank and pumps the water with sponges in the middle, in that I have nitrite removers and a bag for algae removal. I use Nutrafin cycle and Plus to keep the water hardness and stuff right, I also have ph balance to keep it at 7.0. You should also know that I have two Plecos (catfish) in the tank that eat algae and mind their own business, the bigger piranha sometimes try and bite them but they have tough skin and are at least 5cm so the piranha leave them alone. I would GREATLY appreciate any advice or any change that you would suggest. thanks <Principally larger quarters... do plan on moving these fishes to a bigger tank... SOON... and I would add another outside power filter (either hang-on or canister)... for added filtration and circulation... These are gorgeous fish, and you can look forward to enjoying them for many years with good care. Bob Fenner>

Re: piranhas Hello, thank you for your guidance!, I will increase my tank size very soon. could you help me with one last thing please. I want to start feeding the fish some meats to bring out their natural hunting instincts etc.. but I read its not good to feed the fish meat like beef heart but instead raw prawns and salmon. <Actually, some beef heart is not a problem... I had piranhas of a few species for several years and fed this along with other meaty foods> I saw some raw prawns at my local supermarket, are these ok? <Yes> because I know food for human consumption is packed with preservatives and chemicals (and crap). If not where would be the best place to get theses foods? thanks again. <Bait shops, earthworms from your yard/garden, growing mealworms (actually beetle larvae), oriental grocery stores... Bob Fenner>

Piranha/Biological Filtration I read through the Piranha FAQ the other day and found it very informative. I've kept fish since I was very young and have had good "luck" with them. . . I say luck because I've never done anything special- they've pretty much just stayed alive for me w/ minimal maintenance, supervision, cleaning, feeding, or much care at all, really. . . <Good> Well, I currently have a 9" Oscar in a 50Gal, three 3.5" Jewel Cichlids in a 30Gal, and some small tetras in a 5 gal. . . I'm also cycling (for the first time, LOL!) a tank to be ready for some baby Red Belly Piranha. Their beginner tank is 30 gal for five 1.5" Fish and I plan to move them up to a 50, and eventually 100, gallon tank. I've had a Red Belly before (10", solitary fish, died at 10 years old) and am quite familiar with the mannerisms of the fish- at least as a single fish. . . and I'm really looking forward to my new crew! I would like very much to care better for these fish so that they're healthy and grow large. <Sounds good> I've been reading up on balancing the fish's diet, etc. . . and think I'm ready to handle that aspect- my old Piranha ate live feeders only and would go through about 6 large feeders in a week period and fast for three weeks. . . poor fish! I do have some question as to the filtration of the aquarium, however. Since I am new to the concept of a biological filter- although have obviously always had usually more than one per aquarium- I just wanted to verify that I have the right ideas in mind. I'm pretty sure that I've only had luck w/ water quality simply because of my little maintenance or feeding in combination w/ enough space for the fish involved- I never killed off the bacteria or created poor water conditions w/ too much waste (??. . .that's the only explanation I have. . .) <A likely one> SO, to keep my new fish healthy, I have set up in my 30 gal 2 biological filters, each designed for a 20 gallon tank. That's all I have available now and I figured that I can alternate and clean one per month in siphoned tank water. . .will this work? <Should> Do they have to be cleaned, it's just to get debris/waste out, right? <For the most part, yes> Thanks for your help. . .I'm very exited about my new additions! Aja Harris <I encourage you to institute regular water change-outs, gravel-vacuuming... with pre-mixed, stored water... and to add some circulation to the system. Bob Fenner>

Re: Piranha/Biological Filtration Thanks. I do have the tank set up w/ some places to hide, as well as an airstone and a powerhead for circulation and extra oxygen in the water. I added the fish last night- they seem to be doing well so far! <Ah, good> Question about vacuuming the gravel - am I supposed to press the vacuum down into the gravel, or just skim the surface of it? I've always pressed it into the gravel in the past, but am wondering now if that will negatively effect the biological system (??) <Vacuum half at a time... see WWM re...> Also, what are some tips on softening the water and stabilizing the Ph? <Also posted on... WWM> I know they're related. . . I have very hard water (live in Baltimore, MD) and I know that's bad for the fish- it seems to be constantly lowering my Ph as well. I know Piranha like a lower Ph, but I can't keep it above 6.0 for long at all. . . <Actually below...> AND it seems that no matter what I do all of my tanks end up w/the same water chemistry in the end- my Cichlid tanks, my small tetra tank, and now my Piranha tank as well. Hard water (400+), low alkalinity (0), and low Ph (6.0) My ammonia and nitrate levels are at (0) in all as well- at least that's good. . . Thanks! Aja <I'd be investigating and investing in an R.O. device... Bob Fenner> 

Piranhas filtration Hi, I have a 100 gallon tank and 5 red bellied piranhas. I was wondering if a lot plants would give enough oxygen to the piranhas with no top water disturbances. and are there any filters you recommend for the 5 piranhas and 100 gallon tank ( internal and isn't noisy). See I have the piranhas in my room and I cant sleep with loud water disturbances or noisy filters. I wanted to put a lot of plants and an submerged filter. I was wondering the best filter I could use that can be completely submerged and no water disturbances. or are there any other oxygenizing methods I could use? <For this size system, this number of fishes, likely wastes... I would use two good-sized (large) power hang-on the back filters... and if possible, direct their discharges (some you can, some you can't) to move the water in the tank in a large "swirl" or vortex... if not direct-able, I would add a couple of large powerheads (I like the Tunzes, but they're expensive... maybe Hagen or Aquarium Systems lines) in both upper, back corners to generate the same sort of water flow... Only clean one of the filters per week to preserve biological filtration... along with water changes... Bob Fenner>

I'm getting some Red belly piranha's  07/02/05 Is it ok if I only get two or should I get more? And is it cheaper to buy everything together or separately? If you can please help me.               Thank you for your time,                      Jodi Sue Strong <More are better, social animals... if you have the room, mechanicals for them (filtration, aeration, circulation)... a good twenty to thirty gallons minimum per individual. Likely it is less expensive to acquire more gear, livestock at once. Bob Fenner>

Piranha help... basic aquariums 101  - 01/12/2006 Hi there    <Greetings>   I recently purchased a new 65 gallon tank, set it up for a few days and finally purchased 4 new red belly piranha's. <Uhh... hold on a minuto... was this system cycled?> The first day they were fairly active but as the days went on the slowed down and would only float at the top and have no power. <Classic... "new tank syndrome"...> During this time they also developed white spots over their eyes. Finally, all 4 eventually died and I replaced them with 3 more. <Uhh, another moment please... peek-a-boo> This time all 3 looked to be fine until about 4 days into getting them when 2 died and one is now very slow again and developing the white eye thing. Can you please help me figure out what is wrong and what I should do before buying more piranha's?   Thank you   Colin <Time to go back.... way back... Please start reading here: http://www.wetwebmedia.com/FWSubWebIndex/fwset-up.htm then on to the linked files (in blue, generally above...) where you lead yourself. Bob Fenner>

FW chem., too lazy to search WWM... pH Trouble    3/29/06 Hi! I have a Red-Bellied Piranha in a 20-gallon aquarium. <How large is this animal?> Recently I have had trouble with the PH. It has been at extremely high levels  (like 7.6). I've tried to lower it by using Ph Down, but even after using it 3 times the PH has stayed the same. Any other suggestions on lowering PH? Thanks! <... such changes need to occur outside the system... gradually, with water changes. Please see here: http://wetwebmedia.com/FWSubWebIndex/fwph,alk.htm and the linked files above........ Bob Fenner>

Keeping Piranhas with Tropical Fish   10/5/06 Hey, <Hi Ryan, Pufferpunk here> I have a 55 gallon tank. Currently there are 2 small tetras, feeders and a 4 to 5 in Oscar. I am about to put in six 2in piranhas (red-bellies). <HUH?  Are you joking?  Those piranhas, at any size, will eat the tetras (eventually eaten by the Oscar) & bite chunks out of your Oscar!  That tank is just large enough for the Oscar, when it grows.  Don't add any more fish to his tank.  Even a 55g is a bit tight for a full-grown Oscar.> Should I be worried that the larger Oscar might kill the small piranhas?  Likewise, will the piranhas to better if introduced to the tank with no other fish present? <The piranhas should be introduced into a separate tank.  The Oscar will soon eat the tetras or any other fish it can fit into it's HUGE mouth.  I do not recommend feeding your Oscar feeders & find homes, or return the ones in his tank.  They carry disease.  Get him earring pieces of fish, scallops (or whatever you can find in the fish dept of your grocery store that he likes), krill & Cichlid pellets.  ~PP> Thanks, Ryan

Water Conditions for Red Belly Piranha - Natteri Species   9/17/06 Hi guys - love reading your site, really excellent info! <<Hello, Matt, and thanks. Tom with you, by the way.>> I have few questions please on the best conditions for keeping red belly Piranhas. I have just set up a new 275 litre tank and purchased an Eheim 2128 external thermofilter (to my wife's great dis-pleasure due to the cost!) to do the filtering (filled with Eheim substrat pro media as Eheim recommend). <<Excellent choice - and I understand your wife's consternation. Does this count as this year's birthday AND Christmas present to yourself? :)>> The tank is in the process of fishless cycling using Waterlife's Biomature (I will not even consider adding any Piranhas until both ammonia and nitrite are zero as I have the fishes best interest in mind!). <<Always a great pleasure to hear this sort of thing from our readers!>> I have read Bob's recommendation of 80 litres of water per Piranha so plan to buy 3 baby piranhas that can permanently grow up in the tank. <<Sounds good, Matt.>> My questions are around the water parameters for the Piranhas - my tap water PH is 8.0 which seems a bit too high for Piranhas as I think they prefer acidic water - is it OK to purchase a PH lowering product like Nutrafin PH - to get the PH down to just below 7.0 or just leave alone? <<Leave it alone, Matt. It'll more dangerous to toy around with this than it will be to allow your new fish to acclimate/adapt to the higher pH. Perhaps some driftwood would be advantageous here, but chemically treating your water is problematic at best.>> Also my tap water has 25ppm Nitrate - what can I do about this or is this acceptable? (I plan to have lots of live plants so is this level of nitrate beneficial for them?) <<It can be, Matt...with a proviso, i.e. "string attached". Aquarium plants will absolutely use nitrate but it's not their first nitrogen choice - if plants make choices, that is. The "trick" here is two-fold. By keeping ammonia levels at zero, first, you deprive the plants of what they look to initially for a source of nitrogen. This means keeping water conditions pristine, which I suspect is not going to be an issue in your case from what I've been able to determine. Second, healthy, fast-growing plants are a real "plus" here as their nitrogen requirements are greater. Absent a usable supply of ammonia/ammonium, the plants will turn to nitrates for their nutrient requirements. In short, you'll need to "force" your plants to use the nitrates. Now, if you wanted to completely jeopardize your marriage, you could investigate a RO (reverse-osmosis) system for water changes but you didn't get that from me! :)>> I would really appreciate your advice - I want to get everything right before I consider buying the fish! <<An admirable aspiration, Matt, and one that we here at WWM fully support.>> Regards, Matt <<Best of luck in your venture, Matt. Tom>>

Starting my tank   12/19/06 Hello, <<Hello, Tara. Tom here.>> We have just bought the jewel tank containing 190 litres and are setting it up to contain red belly piranhas. We originally wanted 3 but after reading your site discovered that its only really big enough for 2 at a push. <<Given an adult size of approximately 12 inches (30.5 cm), two of these fish would, indeed, be pushing the limit of a 190-liter (50-gallon) tank, Tara. Adequate cover and low lighting should be provided to keep 'skittishness' to a minimum.>> We also would like to know if it is essential to test the water pH before putting in the fish. <<Do yourselves this favor, Tara. Visit the pet shop and find out what the pH is of the water that your future pets are currently being kept in. Piranhas come from waters that are soft and acidic in their natural habitat with the pH below neutral (7.0). This really isn't as critical as trying to avoid introducing them to a tank that's far off from what they've been acclimated to, however. Stability is the key factor here.>> The tank has been set up for nearly 2 weeks now at the right temp and I don't want to be ignorant by hurting the fish by just putting them in without it being perfect. <<pH is not going to be your only concern here. In fact, ammonia and nitrite levels are going to be far more of a concern right now than pH will be. Unless you've taken some extraordinary measures to speed up the 'cycling' of the tank, I doubt that your tank is more than one-third to one-half through the cycling process after only two weeks. Test for ammonia and nitrite (both should be zero) and check your nitrate levels as well. Nitrates, by way of explanation, are the 'end product' of the nitrifying process. If ammonia and nitrites are zero but nitrates are also zero, your tank isn't ready for live fish. Your pet shop can test a sample for you if you don't have a test kit already. Personally, I highly recommend that you get one so that you can do your own testing. Shops have a tendency to tell folks that levels are 'safe' without being specific about what this really means. Better in the long run for you to know 'exactly' what your readings are. More convenient, too.>> Also, what would be your best recommendation to start feeding them as they are only about the size of a 2p when we get them. <<Thawed mussels, prawns, shrimp and fish will be appreciated but there are processed foods, in the form of pellets, for carnivorous fish like Piranhas that they may also take to in order to vary their diet. You might find that early on they'll also accept flake food. (By the way, '2p', for the benefit of our American readers who don't have one readily available, is about the size of a Susan B. Anthony dollar, which is nearly exactly the size of an American quarter. That one might have worked better if George Washington and Ms. Anthony hadn't look so much alike. :) )>> (Although, my husband really wants to feed them live food on occasion. I suppose it's a bloke thing). <<Advise your husband to keep this to a minimum, Tara. Feeder fish have little nutritional value and can be a source of disease. You and I know he's going to do it anyway but, it's not without risk to your pets.>> Thanks for your help Tara <<Consider giving your tank another fortnight (I don't get a chance to use that term very often) to cycle completely and really consider the test kit I mentioned. Uneaten food, if there is any with Piranhas, will need to be removed to prevent your water conditions from becoming toxic. Good idea to stay on top of this as best you can. Good luck with your new additions, Tara. Cheers. Tom>>

Piranhas, Brackish?  2/16/07 <Hi, Pufferpunk here> Are there any species of piranha that live in brackish water conditions?  I thought at one time I had read about this stuff you put into your tank to make it kinda dark and brackish to replicate the Amazon river.  <Dark water is not brackish water.  It is the opposite.  The Amazon river is soft & acidic (low pH)--BW is hard & basic (high pH).> So are piranha's adapted to freshwater for aquariums and normally brackish or are they freshwater or do they live in both?  <Piranhas are strictly freshwater fish.  Dechlorinated tap water is fine. ~PP> PLEASE HELP

Piranha system size --  7/11/07 Hi, I currently have 17 Piranhas in my 45 gallon Aquarium all at about an inch each, because my cousin recently bought the fish but he had to move out of his apartment. The tank looks very overcrowded <is> and I am definitely interested in purchasing a larger aquarium. If I was to get a 100 gallon how many of these fish could I keep and also how large of an aquarium would I have to get in order to keep all of these guys together? <There are several different Piranha species with different territoriality and size, but I assume you have the most common: Pygocentrus nattereri. In a heavy planted and well filtered tank somewhat resembling their natural habitat 20 gallons per fish are the minimum in my opinion. In the usually seen systems with less plants and lots of open space 40-50 gallons would be needed. 5 can be kept in a well planted tank of 100 gallons if pristine water quality can be established, about 350 gallons are needed for the entire group you have. What a tank! Have a look at http://www.wetwebmedia.com/FWSubWebIndex/piranhas!.htm and the linked FAQs above. See fishbase.org for pictures of more species.> Thanks ! <Cheers, Marco.>

Tank questions about 2 different tanks... Endogenous algae prob.s/SW, Piranha tank plant sel.   04/14/2008 Hello, <Hi there> Tank- 200 gal (7'Lx2'Wx2'H), 130+ pounds LR, 40 gal refugium plus a large hang-on refugium, 3-XP3's canisters, 2 Rio 2100 (694gph) and 3 Penguin 1140 (300gph) power heads on sides and back of tank. And a Coralife 220gallon Protein Skimmer.\\ <Mmm, I'd upgrade> Fish- 8" Russell's Lionfish, 3 triggers Niger, Humu, and a Bursa all 4", 2 yellow Tangs 4", 5" Foxface Lo, and a 13" Wolf Eel. I also have a lot of Red Mushrooms, Button coral, and 2 different leathers. And I do a 30gal water changes (w/ RO water) every 2-3 weeks. This tank has been up and running for over 3 years. I get brown algae out breaks, I also have green (hair) fuzz algae on most my rocks and back and sides of tank. I was told since I clean my canisters once a month (not often enough), <This is so... I'd clean them at least weekly> that the entire gunk they collected just creates more Nitrate, lots. What I should do is over time keep the skimmer and get rid of the canisters and add more power heads for more current so that the LR (and refugiums) can do there jobs. (20gph times your tank size ((4000gph)), so I need 1720gph more in my aquarium) Does that sound alright? <A beginning...> I do use Chemi-pure and Phos-Zorb in each filter. I also test water a Reef Master Test kit. My Nitrate and Phosphate are both low and are in the safe ranges but they both show up, always have. <These measures of nutrient ability are not entirely "accurate"... the real bulk of this matter is being expressed, taken up by the algae and BGA (the brown stuff)> I also have allot <Won't correct this time... a lot> of this bright yellowish-greenish sponge (Cecilia I think) <Not this feminine appellation; though a fave Simon and Garfunkel tune> growing on my LR. Is it bad or good? <Mmm, more of the latter> I'm setting up a 90gal (4'Lx18"Wx2'H) FW, I'm going to get 3 baby Red Belly piranhas. I do plan on having plants growing out the top of my aquarium. Just the roots will be in the tank. So with that said should this set-up be OK for 2-3 adult size Red Belly piranhas in the long run? And what kind of plants besides Bamboo should I use? <Yes and if only one, my fave, Ceratopteris> Thanks for all your advice Matt Owens <Welcome. I'd get a better skimmer, perhaps ditch the canister filters altogether, or clean out weekly as stated... add more/new live rock... and likely skip the Serrasalmines (too skittish and boring as you'll see)... Cheers, Bob Fenner>

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