Fruit flies are an excellent food for many surface feeding killifish, closely resembling their natural diets in the wild. They are easy to culture, quickly, cheaply and in large numbers. Fruit flys are rarely available in pet shops, but are widely available online, and very much worth trying, even if you don't bother culturing them on an ongoing basis.

Wild-type fruit fly - Drosophila melanogaster

What is a fruit fly?

Fruit flies are small flies that live on and around decaying fruit and vegetation. They occur worldwide, except the very coldest regions. The species most familiar to scientists, aquarists and herpetologists are in the genus Drosophila which literally means 'dew-lover' in Greek. Also known as 'bar fly' or 'vinegar fly', these little flies are commonly found around waste bins, bars, orchards etc, and they are widely used in laboratories as research animals. The species we feed to our fish however, have been bred to have shorter 'vestigial' wings, and as such can not fly. These are typically from two species Drosophila melanogaster and Drosophila Hydei.

Why fruit flies?

Although dealing with highly mobile flies can be trickier than with worms, there are some great reasons to consider culturing them.

  • Nutritious - all fish can be trained to eat flies, but surface feeders love them. Not only are they relished by the fish, but they also have a high fibre content, and are therefore a great contrast to the fattier foods such as worms and beef heart. They are also typically disease-free, unlike some aquatic livefoods.
  • Prolific An adult fly can lay 20+ eggs in a day. Once you get the hang of it, fruit flies are easy to maintain, and at 25 deg. centigrade the development of Drosophila melanogaster takes just 9 days.
  • Availability - unlike collected livefoods, cultured Drosophila are available all year round.
  • Flightless flies available - fruit flies have been studied in laboratories for very many years, and a lot is known about the humble fruit fly. Over the course of these studies, geneticists line-bred many strains of fly, including vestigial-winged, and even wingless flies. These are the flies typically cultured by hobbiests.
Drosophila larvae in a typical culture
Drosophila larvae in a typical culture
Drosophila larvae climb up the walls of their vials and chrysalise
Drosophila larvae climb up the walls of their vials and chrysalise
Drosophila pupae
Drosophila pupae

Drosophila life cycle

Adult flies lay a lot of eggs. A single female can lay over 20 eggs in a day, and can store sperm within her body for up to two weeks, to lay fertilized eggs at will.

Eggs take 23 hours to hatch at 25 deg C. Once they do hatch, the larvae bury into the media and grow. They will stay as larvae for five days, in which time they undergo three moults.

Eventually they will start to climb the sides of the vial, and when fully grown will settle near the top, and form a chrysalis. The change from maggot to fly takes around three days, but again, is temperature dependent.

The image to the right shows a newly formed chrysalis with the lava's segments still visible (1), an older chrysalis with the fly clearly visible. The red dots are its eyes (2) and an empty chrysalis from which a fly will have hatched (3).

Once the flies have emerged they must be moved to new vials, as there is now no food suitable for them in the old vials.

Fruit fly cultures for sale

Fruit Fly Insect Culture Cups (32oz.) with Vented Fabric Lids - 100 Pack



Fruit Fly Insect Culture Cups (32oz.) with Vented Fabric Lids - 100 Pack Powerful eBay listing templates by 3Dsellers... more

GIANT MICROBES Fruit Fly (Drosophila Melanogaster) Plush



Product Features Giant Microbes Fruit Fly (Drosophila Melanogaster) Plush ToyIncludes A Hangtag With An Image And Fun And Educational Facts About Fruit FlyHigh QualityProprietary designExceptional performance Description: Do You Have A Favorite Bookworm? We Do! And Our Book-Lover Is Sure To Interest Just About Any Bibliophile. SKU:EDIB006H7XM5K Specification Model:'846869001518Item Weight:0.08 poundsSize:'Item Dimensions:0.74x5x5 inchesUPC:846869001518PROP 65 WARNING: This product can expose you... more

NATURAL ASPEN WOOD-WOOL EXCELSIOR for Fruit Fly Cultures, Chicken, Packing - 5lb



5lb Box of all natural Aspen wood wool excelsior. It's great for floral arrangements, as a packing filler, pet bedding with hamsters and mice, hens and chickens. It is also an ideal base for culturing fruit flies when raising Dart Frogs. High bulk light weight. Undyed 100% natural product.This is an all natural product cut from kiln dried Colorado Aspen. It is new never used and does not contain any foreign materials. I see many listing of people reselling Excelsior from things they've received ... more