How to Breed Tropical Fish & Algae Eaters

The ease of breeding tropical fish depends greatly on the species. Some fish require very specific conditions to even have a chance at breeding, while other fish breed so prolifically that you'll have to gender-segregate them. "Algae-eater" fish, which is the most common in tropical aquariums, is the plecostomus, or pleco for short, are rarely bred in captivity -- and they require specific substrates and hiding places to even have a chance at success.

Things You'll Need

  • Breeding tank, 5 to10 gallons
  • Peat moss substrate
  • Plants, preferably live
  • Rocks
  • Flowerpot
  • Sponge-tipped filter inflow pipe
  • Unpainted glass marbles
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Instructions

  1. Universal Necessities for Breeding Tropical Fish

    • 1

      Study the species you wish to breed, including their method of reproduction and their behavior before, during, and after breeding; this is essential to properly prepare for breeding and keep both the parents and offspring safe.

    • 2

      Choose prospective mates that are large and healthy, with no visible deformities and similar color schemes and body shape. Choose fish that are relatively similar in size, as well; if one has to be larger than the other, it should be the female, especially in species where mating fish react violently to each other (such as cichlids).

    • 3

      Give the fish a higher quality diet, including high-nutrient fish flakes and live foods; this should begin in the main tank and carry over to the breeding tank.

    Universal Breeding Tank Preparations

    • 4

      Select a separate breeding tank that is large enough for both parents to swim comfortably in (no smaller than five to ten gallons). Fill the tank at least partially with water from the main tank to both avoid stressing the parents during transfer and introduce helpful bacteria into the breeding tank. Fill the tank lower than its maximum capacity (as low as halfway if the filter inflow pipe permits).

    • 5

      Add the appropriate substrate, if any, for the particular breeding method used by the species (see Section Three); do not use gravel under any circumstances.

    • 6

      Keep the water quality high by using distilled water and maintaining the optimum pH and water hardness for the particular species being bred. Avoid medicating the tank more than necessary as eggs and fry will be very sensitive to chemicals.

    • 7

      Use a filter with a sponge over the inflow pipe to prevent eggs and fry from being drawn into the filter. Set the water exchange rate as low as possible to avoid creating unwanted currents. Keep the water well-aerated.

    Specific Breeding Tank Preparations

    • 8

      Cover the bottom of the breeding tank with two layers of marbles if the fish being bred are egg-scatterers; this will allow the eggs to fall between the marbles, protecting them from being eaten. Use a peat-moss substrate for egg-scatterers that lay adhesive eggs, and heavily plant the tank.

    • 9

      Use peat moss substrate for egg-depositing fish. Plant the tank heavily and include flat stones and an artificial cave (such as a well-cleaned flowerpot on its side) to provide surfaces for eggs to be laid on. Use the peat moss substrate for egg-burying species, as well.

    • 10

      Use peat moss substrate for mouthbrooding fish; they have no other special requirements.

    • 11

      Provide heavy plant growth, including floating plants, for fish that make bubble nests. Use fine gravel or sand for fish that make nests in substrate. Adjust the filter so there is no water current disturbing the tank.

    • 12

      Provide peat moss substrate for livebearing fish. Heavily plant the substrate to provide hiding places for the fry.

    Breeding

    • 13

      Introduce the prospective mates to the breeding tank. Watch for overly aggressive behavior and separate the pair using a glass separator if necessary.

    • 14

      Continue feeding the fish high-quality and live foods. Add water (about five percent of the tank's maximum volume) that is slightly softer than what the species is used to to simulate rainy conditions.

    • 15

      Watch carefully for spawning and egg-laying behavior. Remove egg-scatterers, egg-depositing fish that do not care for their offspring, and egg-burying fish once the eggs have been lain; only mouth-brooders and nest-builders should be allowed to remain with their eggs (and in some nest-building species, such as cichlids, you must remove the female immediately after laying eggs or the male will attack).

    • 16

      Remove livebearing fish from the breeding tank after giving birth to prevent them from eating their fry.

    Breeding Plecos

    • 17

      Prepare to transfer the potential mates to a separate breeding tank unless the main tank is very large (at least 200 gallons), as large plecos can be very territorial.

    • 18

      Cover the breeding tank bottom with peat moss substrate. Place numerous rocks, wooden logs, and plants to provide cover for the prospective mates. Include stone caves (either artificial caves or caves carefully constructed from balanced stones) or a large and well-cleaned flowerpot on its side to provide spawning locations.

    • 19

      Introduce the potential mates to the breeding tank and provide nutritious food (such as spirulina wafers or finely-chopped vegetables) to promote breeding behavior.

    • 20

      Watch for spawning and egg-laying behavior; during spawning, the male will lure the female into a cave, cause her to deposit her eggs, and then fertilize them. Allow the plecos to stay in the breeding tank with the eggs and fry; if you're breeding them in the main tank, the male pleco will protect the eggs and fry from other fish.