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FAQs on the Characid Fishes 

Related Articles: Cardinal Tetras; A School of Beauty, Part II,  by Alesia Benedict, Characid Fishes

Related FAQs:  Cardinal Tetras, Neon Tetras,


Green neon tetras for large tank question     5/29/17
<Hi Andrew>
I am getting to stock my 120 gallon planted tank. It's been set up for over a year but so far only has shrimp and Otocinclus. The tank is heavily planted with plenty of stems and hairgrass, filtered by 2 Eheim 2217 (cleaned monthly) and receives a weekly water change (30-50%).
<I'd like to use the change water on my house plants>
The main fish will be a school of green neon tetras (Paracheirodon simulans). Tank mates will be 20 Corydoras similis, 4 Otocinclus, 75 Amano shrimp, and probably what will end up being 100 or more tangerine tiger shrimp (after breeding).
<Sounds good>
*How many tetras can I get while still keeping the bioload reasonable?* I'm not concerned with nitrates and phosphates (as it is I have to add some daily for the plants), but rather other dissolved organic compounds. I've
found minimizing these to be essential for planted tank health. I'd love to have a large number to see the social interactions at their best.
<Fifty individuals wouldn't be too many, and would make for a nice school here>
Also I run the tank at 74 degrees - is this too cold for them?
<Mmm; yes; as well as the other life listed... I'd raise this to 77-78 F. for all>
Many fish database sites seem to list a wide temperature range for this species.
<Tis so>
<Welcome. Bob Fenner>
Green neon tetras for large tank question /Neale      5/29/17

<<No real disagreements with BobF., but would remind you that this species is very Cardinal Tetra-like in requirements; as Bob suggests, middling to warmish conditions preferable to cooler low-end tropical (i.e., the
opposite to true Neon Tetras). Avoid strong currents, but ensure a good oxygen level by under-stocking the tank and providing steady but gentle circulation. Softer water also essential here; not necessarily mineral-free, but lowish, maybe 2-5 degrees dH, certainly no more than 10 degrees dH. Keep the pH between 6 and 7.5 depending on your ability to maintain stable water chemistry. Specifically, if you're using carbon dioxide fertilisation, for example, link this to pH, and perhaps use a commercial Discus buffer to ensure stable conditions. Green Neons (Paracheirodon simulans) have a poor survival rate in busy community tanks, so choose tankmates accordingly. Small foods, fed in frequent but rather small amounts rather than one feed per day probably best. Bob is spot on in
suggesting a big school is best here -- Paracheirodon simulans does not do well in the usual 6-10 specimen schools people often buy. Cheers, Neale.>>
Re: Green neon tetras for large tank question     5/29/17

Thanks for the information and welcome! What an honor to get information from the man himself, Bob Fenner.
<Hee heeee. Just a petfish kind of guy Andrew>
I look forward to interacting more with your site in the future. I only discovered it recently but quickly found
it to be a wealth of knowledge.
Wishing the crew a happy Memorial Day holiday,
<And you, BobF>

Hydrolycus scomberoides   7/20/11
Is it possible to keep Hydrolycus scomberoides successfully? I'm told they die at 12" in captivity after approximately two years. What conditions would be necessarily (if possible) to keep them long term?
<Hello Rob. There are a couple of obvious problems with this fish. The first is that adults come from very fast flowing rivers with lots of oxygen, and the second is that these fish are extremely large when mature, potentially over 1 m/39 inches in length. Also bearing in mind that these are schooling fish to some degree, if you had three specimens 60 cm/24 inches in length, you'd need a tank upwards of 500 gallons in size, and be providing water turnover rates 10 times that, i.e., 5,000 gallons per hour. Outside of public aquaria, it's hard to imagine many people having those sorts of resources. On top of this, these fish are difficult to feed, and have a definite preference for live food. Those aquarists who elect to use feeder goldfish and minnows may be able to feed their fish in the short term, but in the long term such foods create serious health problems as you hopefully know, partly because of exposure to diseases, but also because those fish contain fat and thiaminase that cause damage to the fish over time. So anyone buying these fish would need to either breed safe feeders at home (for example livebearers that could be gut-loaded) or else concentrate on things such as earthworms and river shrimps (again, gut-loaded). All things considered, these fish are not suitable for the home aquarist, and yes, they all seem to die once they reach a size of 30
cm/12 inches, the length at which wild fish switch from being stream-dwellers to river-dwellers. Cheers, Neale.>

TigerFish (HYDROCYNUS VITTATUS) Dear Bob I would like to enquire about a market for live tiger fish. Is there a market for live tiger fish? <Yes, but a limited one... do to their size, voraciousness, and difficulty in shipping (they don't move well)> Who would be the best candidates to purchase live tiger fish? Could you let me know if it is possible to export live tiger fish to the USA? <If I were a supplier, I'd try various freshwater wholesalers... or if you just wanted to sell to one, contact Steve Lundblad at Dolphin International (Los Angeles) re> Would it be possible to give me a couple of names of live fish distributors in the east (Japan, Taiwan, Thailand, China)? <Please see the O.F.I.s listing here> I heard from someone that there was a big market for these live tiger fish in the east, but after searching far and wide, I have not been able to get any detail ... Please can you help? Freddie <I don't think this market is large... I would look into selling at least other African species as well... Bob Fenner> Midnight massacre - help! This last week I have been losing my albino Longfin and zebra Danios during the night. In the daytime these mainly occupy the top layers of my aquarium, but ay night sleep in the cover of numerous plants and rocks. Each morning I find their numbers diminished and some with their tails completely chewed off and bloodied stumps. There is no indication of the culprit during the daylight hours, but I am wondering if my golden algae eaters are to blame as they seem very protective of their personal space. My tank:           300ltr  (80gal) with mix of artificial and live plantings Temp:              21oC      (70o F)  as I have a mix of goldfish and semi-tropicals PH:                  7.0 - 7.1 Ammonia:        0 ppm Fish:                Comets, Shubunkins, Calico Ryukins, Fantails                       Buenos Aires Tetras, Black Widow Tetras, Bitterlings                         Golden Algae Eaters, Chinese Algae Eaters                         Peppered Catfish, Tandanus Catfish                         Albino Longfin Danios, Zebra Danios I have suspected the Tandanus Catfish, but there is only one, a juvenile, no larger than the Danios. Until now, these fish have been socializing quite happily since installing this tank about three months ago. Can anyone enlighten me please? < My money is on the Buenos Aires tetras. These tetras are quite active and have appetites to match. I suspect they are out looking for a little midnight snack and find these albino Danios easy to find in the dark and easy to catch when they are asleep. As these tetras grew larger they have found that they can now eat at least part of these Danios when they catch them.-Chuck>

Re: Massacre Thanks for your input Chuck. With your advice in mind, I removed the four Buenos Aires tetras to my emergency "hospital" tank, but the carnage continued. Last night I did some torchlight surveillance and located the culprit. It was indeed the Tandanus catfish! Even though he was only slightly larger than his prey, he sure could open wide! Have found out that this breed can grow ENORMOUS, so as he is a native of Australia, he has been removed to one of the dams on my property. Peace now reigns. Thank you once again. < Australian fishes are rarely found outside there native country and so are very rare in the aquarium hobby or in the aquarium literature. You bring out a good point in that aquarists should research proposed tank mates prior to introducing them into their aquarium.-Chuck> Lois

Head and Tail Light Tetra Hi!  I have head and tail light tetra in my tank.  Water is fine.  Ph and all that are normal.  One of the fish is swimming vertical.  Is this a problem? Chris Casey <<Hello. Yes, it's a problem. Please get your water tested, ASAP, at your local fish store, or buy your own test kits. Test the following: ammonia (should be zero), nitrites (should be zero) and nitrates (should be as low as possible, between 20-60ppm is a decent range to aim for). If any of those test high in your tank, water changes will be required to bring them down and control them over time. IF you have had these tested, please tell me the results. You will also need to give me more info on the fishes symptoms, so I can tell you if the problem is treatable or not...-Gwen>>

"Freshwater" "Lionfish", Red Belly Piranha I was just wondering if that you can put a (fresh water) lion fish in with a fire belly piranha. <Well, unfortunately, the "freshwater" "lionfish" is actually a high brackish to fully saltwater animal, and will not last long (if at all) in freshwater.  Beyond that, it is not a lionfish at all, but a toadfish.  The one most commonly available in the aquarium trade is Batrachomoeus trispinosus.  More on this fish here: http://www.wetwebmedia.com/batrachoididae.htm and here: http://www.fishbase.org/Summary/SpeciesSummary.cfm?ID=10747&genusname=Batrachomoeus&speciesname=trispinosus .> The piranha is about 8.5" in length.  Who would eat whom? <Provided that the lion survived long enough to be eaten, I'd name him "dinner" and not get attached, to be on the safe side.  But really, I would absolutely not try to keep this saltwater fish in fresh water.> The fish tank is a 33 gallon tank. <Yikes.  This tank is too small for the piranha alone, in the long run, as it grows to be at or over a foot long.  I would *certainly* not add any fish, compatible or not, in this tank.> Also how can you tell between a male and female piranha. Please send pics, if you have any. <You can find the WetWebMedia article and photos on piranhas here: http://www.wetwebmedia.com/FWSubWebIndex/serrasalminae1.htm .  Sexing this fish can be difficult to impossible.  Upon maturity, the females may be more robust in the belly, and males may have slightly more blunt heads.  I would recommend using http://www.fishbase.org/search.cfm to find out more about this and other fishes.  Here is their info on the red piranha, Pygocentrus nattereri: http://www.fishbase.org/Reproduction/FishReproSummary.cfm?ID=4501&GenusName=Pygocentrus&SpeciesName=nattereri&fc=102&stockcode=4699 They have quite a great deal of information on this fish, please be sure to make use of the links at the bottom of the page.> Thanks,  Travis <Wishing you well,  -Sabrina>

School's In Session Long story. I have a 5gal tank, for lack of expenses, though I have heard that 20gal is better. Last week, out of compassion or whatever, I tried to save some goldfish some people on my college campus were not treating right. Oops. Found out later that they are not good starter fish. Well they all died within a few days. I had not given the tank enough time to cycle. I was told that I could get a couple fish to put in here for starters. Three days ago I got one Serpae tetra and one black skirt tetra. The man at the pet shop said they were his favorites to use. Later that day, I found out online about the schooling fish, and that they need to be in groups of six minimum. What do I do? They seem healthy so far, active. <Well, I would give your tank a little more time to finish cycling, then you might want to add maybe two more of each. Not exactly a school, but small groups> I realized yesterday that I was overfeeding, so I have cut back to once a day, smaller pinch. Water is clear, but there is a smell, reminds me of urine. No other way to put it... Here are my questions. is the smell something bad? how do I get rid of it? <Well, if it smells like urine, it may not be a good thing. A healthy tank has an "earthy", pleasant smell, not an ammonia-like smell. What kind of filter are you using? If you are not already (and assuming your filter can accommodate it), try using some activated carbon. That will help remove discoloration and odor. And, of course, in a small tank, you should be diligent about regular water changes! Acquire some test kits: ammonia, nitrite, nitrate. By regular water testing, particularly in the early stages of your tank's existence, you can really get a handle for what's going on.> Would the two groups work good together, or do I need eventually to get a separate tank? <I think that they will work with diligent attention to maintenance, but you will eventually have to get a larger tank to accommodate these fish at full size. Maybe neon tetras would be a better choice for the long run?> To add fish, how big a tank do I need for a good number? <Maybe a 10 or 20 gallon tank. This would give you more flexibility> Don't have the gages yet, but will be getting them soon. Any help will be so appreciated. Thanks for everything. I've been reading and it's good info. Amy <Keep reading and learning! You're doing great! Scott F.>

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