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Black Moscow Guppies

Pocillia retculata

Male Black Moscow Guppy


Guppies are the most popular live-bearing fish kept in aquariums.  Years ago (1952 to be exact) I began my journey in the aquarium hobby with guppies.  They were easy to breed, interesting, colorful, and hardy.  They were the perfect fish and, because of them I became “hooked” on tropical fish.  As I grew in the hobby, I began keeping other species and eventually stopped keeping guppies.  Only recently have I begun keeping them again.  The variety of color and flowing finage in the guppy strains today is truly amazing!  I marvel at the patience and time that breeders must have had to develop these beautiful fish.  One striking variety with amazing fins is the black guppy.  The broad tail fins of some male specimens are close to half moon with a long flowing dorsal.  Even females have black in their fins and long dorsal fins.  I found these fish to be a bit touchy as to hardiness, but that is common with black strains of fish.  Half or less of a batch of fry might survive to maturity, even under good conditions.  They are not known to be especially prolific, although one female produced 55 fry in one batch for me.  Sporadic small batches may be more common with these fish.  They are especially talented at finding and eating newborn fry also!


Keeping guppies is basic.  A variety of quality foods and clean water are essential.  Blackworms, daphnia, frozen brine shrimp, and a quality flake food will keep them healthy.  I use a flake food mix that is 50-75% spirulina to supply the vegetable matter they need.  Many guppies may survive just on dry food, but I think these would not, and black worms especially are helpful in breeding them.  Clean water can be attained with frequent water changes, filtration, and scavengers such as snails, bristlenose plecos, and corydoras catfish.  The black strain is especially sensitive to pollution, so care must be taken to not overfeed and to make enough water changes. Guppy lifespan is 2-5 years and females reach a maximum size of about 2 inches.  Their temperature range is from 65 to 80 degrees with 75 to 78 about optimal.  I like to add some hardness to their water by using a dolomite undergravel filter, adding seashells to the tank, or adding 1 teaspoon of salt per gallon, because guppies like medium-hard to very hard water.


Very few fry survive in the parents’ tank unless the parents are young and the aquarium is good sized.  Expectant females can be placed in a tank alone with plants, a breeder trap to isolate the fry, or a net breeder.  I sometimes have used a large net with a fine enough mesh draped in the tank full of plastic plants.  The female can be put in this net to have her fry without the stress of being removed from the community aquarium and its water.  The babies are then removed to another tank and raised for 3 or 4 weeks before putting them back in with the parents.  The fry begin eating right away and can eat newly hatched brine shrimp, microworms, and finely ground dry foods.  Those who wish to develop or improve a strain should sex and separate them around 3-4 weeks for selective breeding.  Keeping a strain pure requires a lot of culling, starting with “sliders” and the smallest fry in each batch.


Guppies are fun, colorful, and interesting fish to keep.  I am glad that I am keeping them again---after over 50 years!

Female Black Moscow Guppy