The Spawning of the "Zebra Pleco"  (Hypancistrus Zebra)

Kevin Korotev

was not a fish keeper in 1997 when I saw my first “Zebra Pleco”. They were hanging out among the small, perfectly stacked pieces of slate on the bottom of a 75-gallon tank in the apartment of my neighbor, Jeff. I became so enamored with the fish that I made up reasons to visit him. During one of these visits, I ventured to mention an old dream of keeping a few goldfish in a 20 gallon long. A few days later, after a trip to Jeff’s basement where he kept his collection of once-used equipment, I had everything I needed. I bought the goldfish, but imagined them with black and white stripes.



Female "Zebra Pleco"

Male "Zebra Pleco"

"Zebra Pleco" 3½ months old


Jeff had collected what few articles he’d run across in the three years he’d kept his trio of Hypancistrus zebra. There was little information available so what he had we revered as TRUTH. We discussed all the care and feeding issues, but always returned to the basic and first questions: “Is there a pair?” and “How do we get them to spawn?” As to the former, Jeff could quickly spot the male and declare which of his 2 females was gravid, it was not bravado. He can come to my house today and accurately do the same thing with my fish. Some people have it...By the spring of 1999 I had developed into both a novice fish keeper and an Internet junkie and these two new worlds were explored simultaneously. 

To be a fish hobbyist is to be an Internet explorer and vice-versa and the two are interconnected. It seems natural then that when I was ready to buy my dream fish I would shop in cyberspace. The other, somewhat more practical reason was the local fish store prices on wild caught Hypancistrus zebras starting at $45.00 each. The experience of ordering fish on my computer and then shipping them through the United States Postal Service (or any other service) still makes me grin. The fact that a fish can live in a bag, be sent in a box, fly hundreds of miles at 30,000 feet and arrive alive after no less than 24 hours is some kind of what? Magic?. Opening a shipped fish box is like pulling rabbits out of a hat to me. When mine arrived, I pulled out 4 rabbits. Unfortunately, only three made it, 2 males and a female. The trick was, and remains, faulty.  It’s important to note that only one of these first 4 fish (the dead won was immediately replaced) are involved in the spawning event 15 months later that prompts the writing of this article.

In all the other research I’ve done, this percentage does not present itself as unusual. It is even reflected in my tanks today. If you plan to purchase or continue maintenance on a group, consider the possibility that only 1 in 4 fish are sexually active. Your odds of success are then proportionately better if you have more fish (Universal truth). Of all the sometimes wrong sometimes inspired tricks I tried over the next 13 months I’ve come to believe that only a few of them really matter. I say that, in part, due to the things I learned from one of the two people I know (through correspondence) who have spawned Hypancistrus zebra, Carol Ann Nellen In September 2000, Carol Ann anonymously contacted Wendy McKenna, a trading friend of mine near San Francisco, California. She wanted to sell her “Breeding Adult Zebras”. Wendy immediately contacted me and through a series of events I became the owner of 4 of these fish. Their story deserves an article of its own, but for now I include these edited e-mail excerpts. Know that Carol Ann’s fish ranged from 1.5 years to 7 years of age at the time, she had 6 adults and was recently finding spawn and/or fry about every 6 months.

Information contained [in] brackets is mine, gleaned from other conversations. Below is Carol Ann's e-mail.

<Tank: 36 inches long, 17 inches high, 12 inches deep [29 gallons], Equipped with an undergravel filter, 2 large power heads, a large canister filter and custom hood with special high intensity lights. Lights came on at 7am and went off at 7pm. Since these are fast water fish, I made sure there was plenty of water flow. Gravel was a mix of natural and minor dolomite about 2 to 3 inches thick. Good sized pieces of driftwood with many zebra size creases and holes were piled so high that some of it stuck out of the water. One little tank cleaning Otocinclus and lots live plants completed my setup. I used city water that I conditioned. Generally this [South San Francisco water] is sometimes mixed with well water, very hard and very alkaline. I adjusted to a pH [with a brand name pH reducer] of about 6.5 and used [brand name water conditioners]. Water was kept between 80 and 83 degrees. When I changed water--1/3 to ½ volume every second or third week--I’d sometimes put new water in at a little warmer temperature. Breeding was often initiated after a water change. Zebras were fed flakes [and] tablets only. Once in a LONG while, I’d throw in an algae wafer, but I don’t think they appreciated it. ><When I discovered eggs [between 5 and 7 at the time], usually while making a water change, I removed them and placed them in a quart Mason jar with water from the tank. I also put in a splinter of driftwood and a piece of live plant in the mason jar with the eggs, but made sure no snails or snail eggs were on these. I put an air stone covered with some filter wool about 2 inches above the eggs and put a piece of sheer curtain material or any other thin light porous fabric over the top of the Mason jar. I just used a rubber band to keep the material and airline in place. The jar is placed back in the tank, resting firmly on the gravel bottom. The air stone was a surrogate father. The curtain material covering the jar top kept any snails or other fish away from the eggs. The air stone tubing may have to be crimped a little to keep a light bubble. You want the air to escape through a pinhole in the material as a small stream of bubbles ...not get trapped under the material and "burp" hugely. If the air is too forceful, the eggs get banged about and the water from the tank is not exchanged well with the water in the jar.><The big white eggs hatch in about a week. Without good eyes, you may not even notice that the babies have hatched. They look like a little wiggly hair on top of the egg. As they use up the yolk sac, they start to get their black and white stripes. Within a week, they look like tiny adult zebras. They will not be able to move about or eat until most of the egg sack is absorbed. I fed the babies [brand name fry food]. Careful not to overfeed. If you notice any competition between babies or there is a very large clutch of eggs, you may want to separate the kids and use more than one Mason jar.><If there were only zebras in my tank, I let the babies loose in the tank when they were about 1/4 inch or more long. To play it safe, I covered the intake of the canister filter with filter wool so the babies would not be accidentally sucked into the filter. I changed the filter wool every other day. Also make sure that the usually unused air tube openings on power heads are blocked so that the babies will not be sucked into the power heads through those small openings. I tend to overfeed my fish and rely on the good filtration system and water changes to keep the water quality up. The babies seemed to find plenty to eat in the tank. Adult zebras don't hurt the babies from my experience and the babies seem to hang with the adults for protection.>
<Carol Ann Nellen. Fall, 2000.>

13 months after receiving my first zebras in the mail and trying every trick I could to get them to spawn, I discovered a surprise birthday package in their tank. The following e-mail (to fellow Milwaukee aquarist, Tom Wojtech) acts as a snapshot of the conditions on August 20th, 2000.

<Tom, My Hypancistrus zebra spawned last night.
pH = 7.0 Temperature = 80 degrees 15 days since last water change (I was in the middle of an experiment) LOTS of current in a 15 tall.
Black worms and "Carnivore" pellets every other day (and then too much) I believe the pair that spawned are from a trio I bought 13 months ago (and were about 2" at the time). 2 others in the tank.No obvious weather activity. Maybe a dozen 4mm eggs discovered during a water change. First spawn. R/O to tap mix at 40ppm. 1 ceramic cave/vase (for the dominant male to CLAIM) buried amidst "Lace" rock.>

I was not entirely surprised by this event. The older female was quite gravid and there was a marked increase in activity over the final few days. The spawn was infertile, but that was not surprising either. It was their first spawn and I actually half expected it. The thing that DID surprise me (and eventually helped convince me that conditions did not have to be PRECISE at all times) was that the spawn occurred under pretty poor tank conditions. My e-mail mentions an experiment. I was in a very simple “Let it go” mode and the big pay-off WAS to be triggered by a big, cool, Corydoras-like water change sometime in the next week. 



Setup for "Zebra Plecos"


45 days later, with my 4 fish combined with the “new” 4 from Carol Ann, the pre-spawn activity began again. The time between noticing the activity and the departure of the female can take 3 days!. This time it was my older female (the same as in August) courting the apparent Alpha male of Carol Ann’s. The two challenge and wrestle and line themselves up (in my tank it happens in a cave/vase). The female lays the eggs and is chased out by the male who then moves in/over to fertilize them. If you have ever kept and spawned any of the bristlenose Ancistrus, the activity is identical. Once the male is “on Guard”, he is almost impossible to remove…and you don’t have to if you use a portable cave/vase device. You can, as I did, remove the entire item, male and all, into an isolated incubation tank with similar water conditions. 

Eggs seen in ceramic vase

On the third day after spawning, I was surprised to find 3 escaped wigglers.  These fry never returned to the vase and gave me a perfect ‘control’ by which to gauge the growth of those remaining in the vase. On the 11th day after spawning I decided to forcibly remove the male. 13 fry tumbled out to join those that had developed on their own. 15 stripy little sac-bound miniatures at nearly 3/8”. One of the escapees died, it was my only mortality. There are excellent egg and fry development pictures in the January, 1996 TFH magazine article, “New Information on the Zebra Pleco”. Do not, however, pay too close attention to the captioned day counts. The rate the fry use up their egg sacs seems temperature related. As my zebras spawned in slightly cooler than recommended temperatures, the fry were raised in the same.

I became concerned when the "control" fry still had huge sacs when the pictures indicated they should be gone. I even posted a few panicked messages on the Internet (Catfish Digest) about it. In retrospect, I am tempted to believe that these lower temperatures (under 84) might help the fry development by slowing the process. Yolk sacs might "burn-up" too quickly in warmer temperatures. Underdeveloped fry may die off starvation. This is just a theory. I’m in no position nor mood to try and prove it.


First spawning setup

I did not feed my fry while they were sac-bound. Some suggested that baby brine shrimp would be a good food at this time, I disagree. Sac-bound fry do not eat and the food only fouls the water. Once they were sac-free, they ate like pigs, but only for a few days. They quickly became night only feeders and by week 6 they were being fed on the same schedule as the adults,with heavier feeding on one night and lighter feeding on the next. I’d like to include here what information I have about the 2 remaining adults of Carol Ann’s. Her entire set-up, as described in her e-mail excerpts, was sold to Jan Carpenter of Fremont, California. Jan maintained the set-up as Carol Ann had and was quickly rewarded. Here are some e-mail excerpts.

I just went to clean out my zebra tank and 3 babies about a quarter inch long dropped out of a piece of driftwood!!! Somebody's been busy in there. . Judging by the '96 article [TFH], I'd say they're about 2-3 weeks old given their size and evident striping. Those little sneaks, I never saw a clue that they were breeding in there. . .I can't wait to run this experiment again and actually see the eggs and know what's going on. I guess the babies found something to eat, I wasn't giving them anything special during their infancy. The article suggested feeding baby brine shrimp, but at this point I think they might be too big to eat them. They look more like they could handle adult shrimps>

Jan eventually found a total of 8 fry, but wrote me this news about 7 weeks later:

<I still have one zebra baby alive and thriving. The problem seems to have been a very high nitrite count. When I did water changes, I did very small changes with tap water and counted on the tempering effect of the driftwood to correct the pH which apparently it did since the pH was 7.0 when I tested it [Jan reports her tap water pH at over 8.0]. . .>  
<Since I was doing such small water changes on both tanks, I wasn't cleaning the gravel well enough - hence the high nitrite. This, I believe, caused the death of the other 7 babies. . . >
<(When I told you of all the meat alternatives I was offering as food, it was because) I saw no interest in the meat I offered. I was desperate to find anything that might interest them because I thought they must be starving. I now believe that the nitrite was making them so ill, that they had no appetite. Currently he [the surviving fry] eats blood worms, microworms (oddly), and daphnia among other meat choices. I think he is now eating the brine shrimp too, but am not sure. At best, he does not prefer it. . .>
<I have the vases in the big tank, but I think the adults were also feeling the effects of the high nitrite count, and have not reproduced again. They have, to date, shown no interest (even passing) in the vases. I'm guessing that it will take them a bit to get back to normal.>
<(On temperature)
The temperature in the big tank was 84. 4 of the 8 fry died in there before setting up the 5 gallon [hospital tank]. The 5 gallon was at 82 degrees, now I keep it at 86. I think the babies like the warmer water even more than the adults. . .>
<(On aggression)
I don't know about removing the adults. I often saw the little guys hanging out with the adults and no one seemed to mind, in fact when I first found them, there were 2 young hanging out with an adult in a hole in the log. I suspect that if there's enough space and hiding places, they don't get as protective of territory; Especially with young ones. I've never seen any aggression towards my 2 adolescents either, and they're about half grown now. Then again, maybe they just didn't feel up to the task of running off the competition. Not enough good data yet on my experiences.>
<(On pulling fry)
I wish I knew how many eggs hatched in my clutch. I found 8 babies, but don't know how many I may have started with. That might give some indication of how dangerous or innocuous the adults are toward babies. In keeping with the "better safe than sorry" strategy, it certainly wouldn't hurt to isolate the babies. Another thing to consider, maybe the other adults didn't like having fry around that were not their own. I have 3 adults and 2 juvenile zebras in the 30 long, but there are thousands of places to hide in there too.>

I’ll end this now overlong article with what, in my opinion, are the basic requirements for the best shot at breeding the "Zebra Pleco" Hypancistrus zebra.


"Zebra Plecs" at 5 weeks old

1) Have a young adult pair. As I mentioned earlier, only the one female of my original 4 fish was (and still is) spawning, that’s a 25% probability. Of the 4 adult fish of Carol Ann’s that I bought, only one has been involved in a successful spawn, same odds. If my experience is representative, 2” fish need another year or more of conditioning. Jeff’s 3 remaining fish, over 6 years old now, have never (apparently) spawned and have remained about 3 inches. Carol Ann’s fish, some of which may be 7 years old and nearly 4 inches, are big, beautiful adults, but may be past their prime. There is too little information known to say for sure.    
2) Feed meat. I suspect the main difference in clutch size (and possibly in spawn frequency) between the two groups was diet. Mine were fed Black worms and frozen bloodworms regularly.
I tried beefheart once but ended up having to vacuum it all up. I’ve also fed “Carnivore” pellets and small chunk trout chow. All of these foods are very rich and fatty. I have slowly developed an every other (or 3rd) day attitude about feeding the adults. They just don’t need to eat that much when they eat that well.
3) My first spawn occurred in 80-82 degree water. I do not suspect that the higher temperatures recommended in the earlier TFH articles are critical, but I have not tested the theory. I currently keep my breeding tank at 84 to 86 degrees. Remember too that uneaten food rots quicker and algae blooms faster in water this warm.
4) Current is needed, if for no other reason than it reflects the native conditions and aides aeration. It has been my experience however, that they tend to hide a little more in the higher current. When Jeff turns his power head off to feed, his zebras come out and wait!
5) Breeding caves/vases are optional. I would not set-up without them now that I’ve used them. Carol Ann and Jan were successful without them. In a previous BAP article I explained how I built some vases for another cave spawner. The process is simple, the vase, a simple 8-inch clay item readily found in grocery stores and pharmacies, needs its bottom sawn off, the other, smaller end (the original top) is then plugged up with whatever is handy, the final effect is a small funnel with a wide 3 inch opening and no exit. These are the vases my zebras are using now. They were designed after the ‘higher tech’ knick-knack item known locally as Buoy Bells. They’re named for the design of a floating marina buoy on their side. These items are a regional phenomenon and available through the hobbyist who bought the rights to reproduce them. The zebras seem to choose their favorite cave/vase based on its position relative to the powerhead current. It appears that individual fish (males) have individual preferences...or maybe the dominant male gets the place they all want and the rest choose from what’s left. I do not know the answer. The only things I notice consistently are that no one chooses the cave/vase facing the current, nor do any healthy ones choose to be away from the group in some isolated corner of the tank. Some will hang on the fringes of the group, but always WITH the group.

Another spawn occurred exactly 45 days after the one that yielded the 15 fry.  I allowed the male to stay with this cluster. The adult female was also present. I never saw how large the egg ball was, but have no reason to believe it was any smaller than the last two. On the 18th day, the male allowed two fry out of the vase. They were the only two to make it. Ask me in 6 months why I think this happened. I’m bound to have an opinion by then.!

Hypancistrus Zebra
. 12-6, 2000 Written by Kevin Korotev for the SPLASH, the official publication of the Milwaukee Aquarium Society, INC.
Contributions from Carol Ann Nellen, South San Francisco, California and Jan Carpenter, Fremont, California.

Additional information:
Sue and Craig Dalton’s website:
“Suckermouth Catfish of the Ancistrine Group” from Ancistrinae Internet Lecture from
“Catfish of the Month” November 1997 from " Imperial Pleco”
Newsgroup excerpts from
“The Sorrows of Stripes and Smudge” TFH Magazine, September 1993
“Zebra Plecos” TFH Magazine, September 1995
“New Information on the Zebra Pleco, Hypancistrus Zebra” TFH Magazine, January 1996

Photo Credits: Top 3 pictures from Sue and Craigs New Zealand site at  Bottom 4 pictures are by the author.

Editors note: Most of these links above do not work now since this article was first published in 1996.




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