Breeding The Bristlenose Plecostomus

     The Longfin Green Dragon Bristlenose Plecostomus.
            A male is on the left, a female is on the right.

The bristlenose pleco can be bred easily if a couple issues are addressed. If a few aspects of their care aren’t done
          to the fish’s satisfaction then you will be as I was for over 2 years, where nothing I did seemed to trigger a single
          spawn. Today I have to keep them separated as there are now many tanks of fry here with regular, routine production.
          So what made the difference? Though you may get an occasional breeding in the tank provided for your plecos, what is
          described here should guarantee consistent breeding of capable breeding pairs, with maximum yield of fry that are raised
          with few if any losses.

          First off, we are talking about the standard bristlenose pleco, Ancistrus sp., that attains a maximum length of about 6 inches.
          Developed in a wide variety of color morphs, long fin varieties have come into the hobby that are truly spectacular. Today
          they are available as the natural brown, as well as spotted, albino, calico, chocolate, red, and white, many bred in both
          short and long fin varieties. The variety being referred in this article are the longfin “Green Dragon” plecos.

          Easy to sex, the males develop facial growths – “bristles” that are actually soft fleshy branched protuberances.
          The females are slightly smaller with less extensive finnage (but still with long, showy dorsal and tail), and whose
          abdomens can become quite distended when filled with eggs. They need to age close to a year before able to breed regularly,
          and a single pair can be very prolific, having 150 -200 eggs at a time.

          The male will choose an enclosed space to breed in (more on that in a moment), and when a female is ready, she will be
          lured into the cave. The male and she will twist about in the recesses of the enclosure, where she will release the
          adhesive eggs, and he will fertilize them. The female is let go, often with a collection of torn fins and a slimmed down
          figure, indicating they had just bred.

          The male then guards the eggs and fry until they leave the cave, after which only a few will survive. The male when
          guarding the eggs generally doesn’t eat, and with some of the caves, the male is able to form a seal around the eggs and
          fry, so that they can’t even be seen. You will need to remove the fry and raise them up separately, and that will be
          explained later in this essay.

          But first- how do you get them to breed?

          A tank of at least 29 gallons should be used. Two breeding areas at opposite sides of a 55 gallon is perfect. Full grown
          pairs will reach 6 inches, and the adult males, particularly after assuming ownership of “their” cave, can be fairly

          Most hobbyists set out to breed fish that have grown out in their tanks, hearing of others who one day simply looked
          in to see pleco fry. This leads one to think that if you wait for it, it will happen. If you are like most people, your wait may
          be awhile, unless you make specific efforts to breed and save the fry of this fish.

          First off, plecos are catfish, and most catfish require good water quality and some water movement to spawn. They are
          also specific about the structure they choose to breed in.

          The Fish

          You must obtain a sexually mature pair, or better yet, a group, and allow the fish as they grow out and mature to pair off
          naturally. I have found that plecos tend to pair bond, though switching a partner, by removing one, could probably be
          done if necessary.

          It seems to take a while before they become old enough to spawn- close to a year, and determining when they have
          reached sexual maturity is not difficult. Males will grow soft, fleshy, permanent, branching facial protuberances that
          immediately identify them distinct from the females. As well, with the longfin varieties, the males are also larger, with longer,
          more extensive finnage. Though a dusky green color most of the time, the males become almost black when breeding, and
          will maintain that darker color while they are guarding the eggs.

          The females are slightly smaller, with a smooth face. As they become breeding age they will become rounder as they fill
          with eggs, giving the impression they had swallowed a large marble.

          The Pleco Cave

          If they are not breeding for you, you must satisfy variables that could lead to success.. I found it important to
          invest in “real” ceramic caves, as opposed to a simple piece of white or black PVC with a cap at one end. Some feel
          the surface is too slick for the plecos, some claim it’s the color, and some claim to use them routinely with success.
          I know they will breed in natural looking clay fired oval tubes, closed off at one end. Be sure the cave you set out
          will be snug for the pair you have- They search out the tightest, most confining space for the job. Today there are a
          number of makers of pleco caves on the internet that can be bought affordably.

          Tank Size

          The size tank is dictated by the size of the fish you are working with and number of pairs in the tank. Single pairs
          will breed easily in a 29 tall with 4 to 5 inch fish. A few pairs here that approach or exceed 6 inches are bred in
          55 gallon tanks, 2 pairs per tank, but a single pair would probably breed in a 30 if the tank had few other inhabitants.




    The most prolific 55 gallon tank for the plecos.
    Today there are two young sexually mature pairs,
    and two individuals that have not yet sexed out.
    one of these pairs spawns regularly. Many
    spawns have come from the cave on the far left
    and the second one from the right. No males have
    chosen the other two. Alfaro cultratus can be
    seen swimming above. Notice that the caves are
    bent or tilted so that eggs will not fall out.

          Tank Setup

          You want the fish to use the cave and feel secure, but you still want to be able to watch them closely so that you can
          determine when any eggs are laid, and when they will hatch. If you are planning to keep more than one pair in a larger
          tank, you might consider dither fish that won’t bother the pleco eggs or young. Surface feeders such as Alfaro cultratus
          are an excellent choice. The bottom should be bare bottom or with a minimal substrate as they will be eating foods that
          can foul the tank, and could cause water quality issues that could discourage them from breeding.

          Our experience is that the bristlenose plecos generally leave Java Fern, Java Moss and bolbitis fern alone, so using
          small groups of plants for security and natural look works well.

          Though many claim to breed plecos at a wide variety of temperatures, I have found that breeding them at 77-78 degrees
          works best. Moderate to normally bright lighting is fine for them.

          As with many fish that look to spawn in a safe environment where they hope to guard their eggs, try to provide
          opportunities for them to feel secure. Here, we cover the tanks, keep the lighting at moderate levels, and put in a
          thin layer of gravel over about half the tank bottom around the caves and separate from the high activity areas where they
          are fed. Moderate to Heavy aeration is used with some water movement.

          Plecos need easily digestible, highly nutritious vegetable food, and lots of it.
          Feeding blanched zucchini is essential to maintain them in good health, but if
          you wish to trigger them to breed, as well as to maintain them at their maximum
          health, beans can't be beat. The French Cut are necessary, particularly for
          younger fish that have difficulty getting past the skin of whole beans. Others
          have reported good luck using peas. But with any of these, extra filtration
          becomes important to maintain breeding levels of optimum water quality.


          When everything else is in place, the proper foods to trigger them to spawn are often the step that brings success.
          The quickest and most consistent results come from feeding canned French cut Green beans, no salt if possible. The
          French cut splays the beans so the fish can eat them more easily. However, here we must use the 6.5 lb. cans, and
          regular beans are all that is available. They work fine, but with new fry it is necessary to cut them in half so
          they can access the bean to be eaten. In combination with the green beans, a broad higher protein dry food can be
          fed alternatively. Plecos are big eaters, and when setting out to breed them, place green beans in the tank first
          thing in the morning, and try to always keep some available to feed upon. You may find that you will need to
          replenish the beans once or twice more over the course of the day.

          Blanched zucchini is excellent for maintaining them, but does not provide enough nourishment if you are looking
          to breed them. Others have mentioned feeding green peas, but we have never used them here.

          Water Quality

          This is one area that alone will keep your plecos from spawning. They may live comfortably in a tank for many
          years with apparent satisfaction, but if there are routine, chronic water quality issues, breeding may not occur.
          Many fish require water of better quality to breed than what they normally thrive in. Some may claim plecos breed
          without concern for water quality, but for breeding success, and certainly to accomplish spawning if it has been
          a problem, plecos must be treated like any other catfish that requires optimum water conditions.

          This becomes a big problem when you are putting at least a handful each day of green beans into your tank! The
          combination of the mulching of the green beans done by the plecos as they eat them, their waste, and the natural
          tendency of green beans to cloud the water, leads to immediate issues if something isn’t done.

          For this, on a 29 tall or 55 gallon tank, a 250 hang on the side canister filter is used to boost the filtration and keep
          the water from becoming too ammonia rich. Heavy water changes also come into play. Fortunately, young plecos
          seem very tolerant of the cloudy water that follows a bacterial bloom- though I rush to address it when it occurs.
          These canister filters – when using their “micron sleeve” for maximum filtration, should keep the tank fairly clean
          and relatively mulm free. It will need to be changed whenever it clogs up, and when feeding beans to encourage a spawn,
          the filter may need to be changed daily. (The sleeves clean easily by soaking in water and bleach, and two sleeves can
          simply be rotated. However, be careful to rinse the sleeves thoroughly- be sure to sniff each sleeve before using it to
          ensure there is no bleach residue.)

          Yet there is one more solution to this problem. If you are using multiple tanks, I have set up a sump system with a
          pump that runs the water through layers of foam and floss, in combination with the normal tank filtration. However,
          many 10s, 20s and 30s are used to raise pleco fry that are not on a central sump, and with the external canister filter,
          normal box filtration and regular water changes, the tanks do fine.


          When all of the factors mentioned are followed, if breeding is problematic it is because they will breed too
          frequently. Too often, within days of removing a spawn from a cave, the male with have another batch going.
          Plecos are very prolific in the wild as well, so when conditions are to their liking, they will generally
          breed. However, I have found breeding to commence almost immediately if certain things are done.

          With a pair that had bred previously, they were separated for a couple weeks, and then when she was clearly
          full of eggs they were introduced in a breeding tank. He had taken ownership of a specific cave and it was
          moved with him when put in the new tank. They were introduced in the afternoon, and he was guarding eggs by

          On more than one occasion, tanks are cleaned and set up to breed pleco pairs, and when doing so, 20-40% of
          old water is used, the rest is fresh. Often the abrupt water change will trigger them to spawn, and there will
          often be batches being guarded as soon as the next morning after being moved to the new tank. 

          After 5 years of breeding this fish, and logging in the spawns, we are finding that this fish, at least here, is
          breeding seasonally. An occasional spawn may occur at other times of the year, but the majority of the egg
          production will happen from about early-September to early February. With some pairs, all efforts to get them
          to breed seem to fail, when waiting until their season comes around is what they are waiting for. This could be the
          case if the tank is exposed to a window, and natural, seasonal light cycles.

          The Breeding

          So you have a pair in a 29 tall, 78 degree aquarium with some plants for cover, and good aeration in a tank that
          is essentially bare bottom with a thin layer of gravel. Beans are fed throughout the day with a good quality higher
          protein dry food, and a pair of adult plecos, with the female obviously round with eggs swim beneath the stream of
          water coming from the 250 HOT Magnum hang-on-the-side canister filter. A natural cave of ceramic, rock, or fired
          clay at least 5-6 inches long is provided, large enough that the male can get in and out fairly easily (and at some
          point will have the female in there with him), and the cave is placed so that you can see into it (possibly with a
          pen flashlight).

          The male should take ownership of the cave, or will choose one that he will call his own, and he will lay for most
          of the day at the cave opening.

          When the female decides that she is ready to lay her eggs, she goes over to the male, and before breeding they
          will generally both be in good shape. After breeding, they will have spent time rolling around in the tube, and
          will often show slight abrasions and torn fins. The female may also appear to be slimmed down. She may hang out
          near the breeding cave, but is otherwise no longer involved once the eggs are laid.

          The male will become very dark colored following breeding, and will stay slightly in from the mouth of the cave actively
         “fanning” the eggs- his fins will shake consistently for hours to keep water flowing over the eggs.

          New, young males will frequently need to learn to do this appropriately, and will frequently knock eggs from the cave.
          They do not put them back, and you must remove them to hatch and raise them separately, which will be gone into in
          greater detail later in this essay. If the eggs are not saved, the eggs or new fry will likely not survive.

          After 4-5 days, the eggs will hatch, and the young will stay in the cave guarded by the male, until their yolk sacs
          are depleted – they will then venture out looking for food. If you are going to save the batch it is necessary to
          remove the fry and raise them up where they can be fed and monitored properly before this happens. Occasionally,
          after taking 3 or 4 batches of fry away from a male I will let him raise a batch up himself, and rarely do more than
          8 or 10 survive of a batch of usually over 100 eggs.

          This next fry sequence are all of the same batch.


               5 hours old. Immediately they
                 clump together for safety.


          Just hatched. Notice the whitish
         structure the eggs were encased
                     in on the right.
          The second day. each set of tiny
           eyes and a tails sits above the
                     round yolk sac.
                            Day 3                             Day 4
         Day 5. Through this entire time,
         they are not being fed anything,
          and provided with aeration and
            twice daily water changes.
     Day 6. At this point feeding of frozen BBS
     and ground cichlid pellets begin. A few
     green beans are offered and changed daily.
     Day 7. They haven't suddenly become dark
     it is simply the light, but their dark natural
              color has begun to develop.
        Day 8. The lighting here begins to
          show the differences in shading
                 between individuals.

     Day 9- The new pleco fry get their
     own digs in a regular, filtered,
     bare bottom tank. Mulm is kept
     siphoned up about every other

     To the right is a line in
     development, and if all goes well,
     the first of this line to be sold
     will be the young of this generation.
     Not clear in this photo, the body
     length of this fish is nearly half


          Raising the Young

          The best time to “harvest” the young is within 2 days of when they hatch. If you do manage to retrieve eggs – an orange
          colored ball of large eggs attached to one another- this is OK, they can be hatched in the same way the fry are raised.
          I take a plastic tub that will float in the tank where the eggs were laid, the size tub of about 10 x 12 inches and
          around 4 inches deep. This will be floated in the tank (so the temperature stays the same, and multiple daily water
          changes can be easily done with water from the tank it is floating in.) Into this tub is placed an airstone with a
          moderate air flow. If you are hatching eggs, you do not want the bubble stream to be so strong as to disrupt the eggs-
          just keep the air strong enough that it keeps the water gently flowing around them.

          Removing the fry / eggs from the cave- This doesn’t make for the best day for the pleco, and I would rather it were
          a less disruptive process. Take the tub to be floated in the breeding tank, and put about 2-3 inches of water from
          the tank into it. To startle the pleco as little as possibly (causing him to possibly scatter the eggs or fry from
          the cave), I gently but quickly move the cave with the eggs and male pleco in it into the tub. The pleco will
          generally spread out and refuse to be dislodged from the cave. So with a rocking motion, fill the cave with water
          and rinse it out- hopefully pulling eggs or fry with it. Keep doing this until you have the amount of fry you want
          to raise up. I will often leave some of the spawn for the male to care for, or to come back and retrieve later. The
          cave and male are put back in the same spot in the tank, and the tub is lowered into the tank to float and raise the 
          young in until they are ready for a tank of their own.

          All of the young will group together as they would against the wall of the cave for the first 5-6 days. They are
          absorbing their yolk sacs and are not yet eating. However, they are respirating and releasing wastes into the water
          as at any other time, so change about 50% of the water (with clean water from the tank they are floating in) at
          least twice a day. I keep a small cup nearby, and can easily dip out and replace water as I pass by.

          Around days 5 and 6 they will become old enough that they will cease to huddle together in tight groups, and will
          begin to explore, searching for food. As soon as you see them beginning to separate out around the container, feed
          them baby brine shrimp. Now, it is not enough to hatch the shrimp and feed it to them as you would any other fish.

          These baby plecos can only eat what they can crawl over, so the BBS must be accessible to them. After hatching,
          rinse the BBS in a net and mix back into a couple cups of aquarium water, then pour into ice cube trays and freeze
          them to be fed over the next few days. The shrimp are then nearly as nutritious as when live, and are eaten eagerly
          by the new plecos. After recently purchasing a coffee grinder, high quality cichlid pellets are also ground up and
          fed to the baby plecos. They are fed twice a day with each feeding followed by at least a 50% water change within an
          hour or so, before the deteriorating thawed BBS has an opportunity to cloud the water.

          At this time it is also best to introduce either French cut green beans or regular green beans cut in half to get
          them accustomed to foraging on vegetable food. The quicker you can get them on green beans, the quicker you 
          can put them into a tank of their own without losses, as they will be accustomed to eating food that will generally 
          be available. Depending on the number of fry in the batch, size of container you are using, etc., you will likely
          want to get them into their own tank with filtration in 7-10 days. You will know when it is time when most are
          eating the beans routinely.

          Unfortunately, the green beans will cloud the water after a few hours. The cloudiness is caused by a bacterial
          bloom that occurs when the bacteria feed on the deteriorating vegetable matter. Soon the amount of oxygen used
          and the waste produced by the bacteria will overwhelm the container, killing the batch. So all beans are removed
          before nightfall and replenished in the morning, followed by a water change, as long as they are in the confined
          tub. Each evening before leaving them until morning the quality of the water is checked- a problem is any sign
          of cloudiness-, and a quick water change will be done. The airstone should be going 24/7. At first you may want to
          remove the airstone when the fry are feeding on the brine shrimp or the ground food, to be replaced once they finish
          To reduce organic load as the fish grow, cull as soon as you can see traits that are undesireable. With the long
          fin varieties, any short finned fish are removed as soon as they can be identified.

          They will consistently with good feeding and clean water, reaching about 2 inches in 3-4 months, and sexing out
          in 5-6 months.


          Greg Sage

          copyright 2014




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