Updated: Aug 24
Dubia cockroach cultures have, for a long time, been very popular with reptile, amphibian and tarantula keepers around the world, but it may be surprising to learn that many fish keepers culture these insects too.
Eating insects is quite natural as insects and their larvae often constitute a significant portion of a freshwater fishes' natural diet.
Studies into various freshwater species, from pufferfish to stingrays demonstrate that insects are a very important food source. Take the Colomesus asellus (the Amazon Puffer) for example. Almost half of their natural diet (48.63%-49.9%) is Ephemeroptera (mayfly).
Feeding live-insects - as a part of a varied and balance diet - to our captive fish can be very beneficial. This is precisely why many renowned manufacturers now offer insect based fish foods, but culturing livefoods at home provides a level of self-sufficiency, greater control over your animal's diet and direct access to a renewable supply of healthy feeder insects. This is why livefood cultures appeal not only to those who are looking to save money (although saving money is a welcomed consequence), but also those who want the best for their animals. Raising you own feeder insects has additional benefits such as having access to different sized cockroaches, from little to large, to suit the size/type of predator.
Cockroach cultures are not only a very popular choice because of their nutritional value, but also because - compared to other livefood cultures - cockroaches are easy and inexpensive to maintain, require relatively little space and are also very hardy and readily available.
This article will focus on the requirements of Blaptica dubia (photographed above).
The requirements of other species of cockroach may differ.
The B.dubia is a species of cockroach, from Central and South America, which grows to approximately 40–45 mm (1.5-1.77 inches). It is the most commonly cultured species of cockroach and they are known to most as the Dubia cockroach, South-American cockroach or Orange-spotted cockroach.
Their popularity as a feeder insect is owed mostly to the following characteristics:
Their excellent nutritional value
They can not climb smooth, vertical surfaces
They are very slow moving and cannot jump
They are quiet, unlike crickets
They can not bite
They are not capable of sustained flight
They produce a very low odour, unlike some other species of cockroach
They reproduce relatively quickly
They are very capable of withstanding a variety of different stressors
What you need:
A storage container (read Housing)
A Drill (read Ventilation and humidity)
Maybe a heat mat and thermostat (read Temperature)
Egg crate flats (read Egg Crates)
Blaptica dubia mating and lifecycle
Mating occurs when the male deposits a sperm packet in the female. This sperm packet inhibits the female from further mating.
Females then lay an ootheca (egg case) which is incubated internally.
The gestation period is approximately 28 days. After gestation, anywhere from 20 to 40 young nymphs (approximately 2-3mm) will emerge from the female.
The nymphs will reach sexual maturity in approximately 120 days, depending on temperature and nutrition, after approximately seven instars.
Healthy adult B.dubia roaches will live for anywhere between one and two years.
A B.dubia culture requires relatively little space and they can be housed in a simple, inexpensive storage container with a lid, like the one photographed.
They can not climb smooth vertical plastic, but they can scale a slightly textured material. For this reason, the container walls should be as smooth as possible.
For small cultures, I would recommend a 40L container (approximately 10 US Gallons) as a minimum. One 40L container should be a sufficient amount of space to provide a sustainable supply of cockroaches for one or two medium-sized fish.
Really Useful Boxes® are exactly that, 'really useful' for cockroach cultures with their thick, smooth plastic construction and lockable lids.
The size of container you will need is ultimately going to depend on the amount of cockroaches that you are going to need. More demand will require more space for more breeding adults. I recommend starting off small in a 40L and upgrade in time to a bigger container if necessary.
Although this species will hide in the darkened areas of their harbourage (place of shelter) during the day, B.dubia have been shown to be more productive when they have a day and night cycle, which is why I have chosen to use containers made from a transparent plastic.
Egg crate flats
Egg crate flats are a common addition in most insect cultures because they greatly increase the surface area inside the enclosure and offer the insects dark harbourage (place of shelter).
B.dubia prefer dark areas and will become anxious and may not breed without sufficient harbourage.
Arrange the egg crate flats vertically, with cardboard spacers (photographed) to prevent the egg crate flats from fitting together, reducing available space for the cockroaches to utilise.
Stacking egg flats vertically (as opposed to horizontally) helps with air circulation, facilitating evaporation and inhibiting the growth of mould. Arranging the egg crate flats vertically will also cause as any waste created by the cockroaches to carried to the bottom of the container by gravity, rather than accumulating into piles inside the egg cups.
B.dubia will eat parts of the egg crate flats and they do degrade over time. As a consequence, they will need replacing periodically.
You will be able to buy egg crate flats online, but ask your local bakery, café or restaurant who will most likely be happy to give you some, instead of sending them for recycling.
Ensure that the highest level of the egg crate flats are at least 1 cm (0.39 inches) from the lid of the container, to prevent nymphs escaping through the ventilation (read below).
Ventilation and humidity
Whichever container you choose to use, your cockroaches are going to need adequate ventilation to provide oxygen, prevent the humidity from rising too high and provide enough aeration.
I have drilled a series of small holes, 5cm (1.97 inches) apart, using a 6mm HSS drill bit, in the lids of my containers for this purpose.
The humidity in the container should be maintained between 50 - 60%.
B.dubia can tolerate a lower humidity than many other species of roach, but they will not moult successfully and production will decrease if the humidity is too low.
A serious consequence of low humidity is the infertility of the female B.dubia. If the humidity is less than 40%, the ootheca (egg case) dries out which will cause the female to abort that batch of eggs. Occasionally, the abortion is unsuccessful and the ootheca begins to rot internally and this can cause a fatal infection for the female. This is obviously not conducive to a high-yielding culture, so the humidity should be afforded as much attention as possible.
You can increase the humidity by misting the container with a water spray bottle (avoiding the egg crate flats), by placing a water bowl inside or adding a humidifier.
A humidity that is too high can also negatively impact your culture.
A humidity higher than 60% can facilitate the production of growth of mould and bacteria. Not only can mould and bacteria cause a noticeable odour, they can also be dangerous to you and your roaches.
It is much easier to increase ventilation than it is to take away, so I would recommend starting with a series of small holes in the lid (as described above) and monitor the humidity as you go. If you find that the humidity is climbing too high or aeration is too low then you can increase the number of small holes in the lid.
Alternatively, you can drill larger holes than the 6mm holes I have recommended and cover them with a stainless steel fly screen mesh, which you can secure using an aquarium safe silicone.
These cockroaches can chew through fibreglass fly screen, so a high-quality metal with rust resistant properties is best.
I keep my cockroach cultures in my fish room, which has a relative humidity of approximately 60%. The small holes in my container lids are sufficient in maintaining the correct level of humidity and aeration inside, but your environment may be different.
They should be housed in a temperature between 25°C (77°F) and 35°C (95°F). For optimum production, a temperature of 30°C (86°F) should be maintained.
Small reptile heat mats, preferably with a thermostat, are ideal for placing underneath the container (always on the outside) to ensure the cockroaches are kept at an optimal temperature.
Thermostats can be programmed to cut off the power to a heat mat at a certain temperature, which offers a valuable layer of protection against overheating.
Hydrometer and Thermometer
There are several digital units which can read both temperature and humidity available. Check the reptile department at your local pet store.
It is worth noting that some digital thermometers are not entirely accurate, so it is worth testing the accuracy of a digital unit against the reading on a glass thermometer and comparing. Thermostats should also be tested for accuracy.
Adding your cockroaches
Once you have created a suitable enclosure, I suggest starting your culture with at least 100 adult B.dubia cockroaches, of breeding age, which can usually be ordered online or bought in bulk from your local reptile supply store.
Male to female ratio
After a lot of experimenting, I have found that the best female to male (F:M) ratio is between 3:1 and 5:1. When too many males occupy the same space, they become aggressive when trying to mate and will disturb other males during their courtship with females. They are also likely to eat the nymphs when competition for females is too high, because those nymphs will contribute to his problems when they reach sexual maturity. Obviously, we want to avoid that because this is not going to aid the breeding endeavour.
I have found that productivity also slows down above 5:1 and males become less active. I can only hypothesise that some degree of "healthy competition" is good.
B.dubia is a sexually dimorphic species, where the differences between the sexes becomes very obvious as they reach maturity.
Adult males (photographed- top) have full wings that extend to the very end of their abdomen. Their wings do not allow sustained flight.
The adult females (photographed - middle) are larger than the males and lack full developed wings. Instead, females have only small stubs.
B.dubia are most accurately sexed as mature adults, but anecdotal evidence suggest that female nymphs are slightly wider at the base of their abdomen and less "pointy" compared to males, but the accuracy of this method to determine the sex of young individuals is yet to be confirmed.
Good conditions and nutrition results in healthy, fertile and productive B.dubia cockroaches. Healthy cockroaches live for longer, grow bigger (read Stunted growth), produce larger broods and have less mortality among nymphs.
Healthy cockroaches will also provide more nutrition to your fish. Just like varied diets are recommended for fish, varied diets are also recommended for any insect who are going to be fed to the fish and the fish will benefit from the same nutrition that the B.dubia will benefit from.
The most direct causes of stunted growth are inadequate nutrition and infections/disease that cause poor nutrient uptake, adsorption or utilisation.
If the cockroaches become stunted while they are young, in a critical stage of their development, then they will never achieve full size, be a productive asset to your culture and die young.
The primary benefit of culturing cockroaches at home is the ability to gut-load them for the well-being of the fish that you are going to feed them to.
Gut-loading is the process of feeding nutritious foods to the prey, so the predator can derive that nutrition when it consumes the insect. For example, if you want to offer your fish more vitamin A then you would feed foods high in those vitamins.
Dubia cockroaches will eat almost anything, but they are primarily a frugivore; preferring fruits, fruit-like vegetables and other plant matter, Preferred foods for B.dubia as a part of a varied diet include:
Lettuce (not iceberg or romaine)
Quality rabbit food (dry)
Quality dog/cat food (dry)
Commercial feeds are also available, but I would encourage you to carefully consider the ingredients of any products to determine how nutritious they are going to be for your cockroaches.
Although B.dubia will eat meat, gut loading with meat products is not recommended.
High starch tubers such as potato and yam offer little nutritional value and seem to only be eaten for their water content.
You can provide additional water to your cockroaches by adding a shallow dish of water.
However, the cockroaches - especially nymphs - can drown in the water dish. One solution to this problem is to add marbles or pebbles to the dish which will prevent the cockroaches from falling in the water and drowning when they come to drink by offering them an area to walk on.
Products such as ProRep Bug Gel, which is made of polyacrylamide gel, can also be used to provide hydration. However, you can completely circumvent the necessity to add these additional sources of hydration by feeding the correct foods; like discussed above.
Enclosure maintenance and frass
Typically speaking, a cockroach colony needs very little maintenance but you should always ensure that your enclosure is free from decaying food, mould, dead cockroaches and spoiled harbourage.
Frass is a mixture of cockroach faeces, shedded exoskeletons and other organic matter.
Frass is normal in an enclosure and has some benefits to the cockroaches. Frass is one of the first things that newborn cockroaches will eat, second to the discarded ootheca of the female. Frass contains nitrogen which is converted to protein and beneficial bacteria that will help facilitate the development of a healthy gut microbiota in the newly born cockroaches. The gut microbiota plays an essential role in development, digestion, nutrition, immunity and disease resistance.
Frass should be thinned out when it is becoming too deep and spoiled frass should be removed as quickly as possible. Healthy frass is odourless, has no mould, is very dry and loose. It should have no moisture in it and be free from clumps.
Never release non-native animals as they could become a problem for the local ecosystem.
Proteins found in cockroach regurgitates, body parts and excrements can become acute allergens for people who are exposed to them on a regular basis. For this reason, the use of PPE (personal protective equipment) is recommended whenever handling the cockroaches or maintaining their enclosure.
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