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INTRODUCTION AND BACKGROUND:
All of the information provided in this reference page has been compiled by me, but I did not write it. (Save summarization in the Q&A section). The majority was written by Ed, who is a well known and very experienced herpetologist and zookeeper. He is likely the most experienced person on this board when it comes to multispecies enclosures. Some information from other individuals has also been quoted and included in this page and is cited appropriately.
When referring to mixed enclosures, the use of the word mixed is an inapt description as this indicates that the animals are together in a homogenized fashion. Because this is not what typically happens, ‘multispecies’ is a better description of the properly set-up enclosure and will be used throughout this write-up.
Multispecies enclosures are becoming more and more common with the larger and better Zoos (including some of those at the forefront of dendrobatid breeding such as NAIB) and Aquaria. Many of the multispecies enclosures at these institutions have been present for years (some for more than a decade) with little to no problems and on some occasions house multiple generations of the animals on exhibit.
There are a lot of potential problems that get thrown whenever multispecies enclosures are brought up on various forums (not just this one). These include, among potential others:
1) The spatial requirements of the animals are violated
2) Pathogens
3) Stress
SPATIAL REQUIREMENTS:
This is an issue where some hard and fast numbers have become predominantly quoted in the hobby. Usually, people speak about 5 gallons per frog. To make this simple, I am using the assumption that the 5.5 gallon tank is the standard for the 5 gallons that is the commonly used reference.
Within the 5.5 gallons of space, the space used by the frog (I am going to use a Tinc. as a standard for the larger dart frogs) is typically very different than the space allotted. In a typically planted setup, the frog will only use the bottom of the tank most of the time. So the actual total space used by the frog can be calculated by the surface area of the bottom of the tank (8 inches by 12 inches) and, say, 3 inches of head room for the frogs to hop. A 5.5 gallon tank contains 960 cubic inches so the frogs only really use 30% (288/960 = 0.3) of the available space or about 1.65 gallons.
What this means is that people have to pay attention to how the tank is portioned out for the frogs. With the set-up described above (5.5 gallon tank) there may be between 4 to 5 inches (subtracting for bottom of the tank) of height in the tank that is not used by the dart frog. This would indicate that another species could inhabit that niche if the owner of the enclosure was so inclined. In a manner similar to aquariums, people can look at the enclosure as having an upper portion, a middle portion, and a lower portion. In most of the smaller enclosures, this will only be two levels. The other space designates a niche that can potentially be used for a different species. This is where multispecies enclosure planning begins. The person needs to be aware of how much space is really being utilized in the enclosure by the animals. This will give you the first step on the path to the next choice if you wish to keep multispecies enclosures.
To repeat, I am looking at a conservative minimal spatial availability, not the maximum the frogs can/will use (this is an important distinction). So even looking at the minimal space available to the frogs in a more complex set-up such as those that include drip walls and plants, the ratio of habitable space still decreases as the volume of the tank increases. As more and more of the volume of the tank is represented by glass and air volume there becomes less habitable space for the frog. However it is this change that creates the changes in the moisture levels, humidity, air flow patterns, and light patterns that create different microhabitats which allow additional multispecies options.
If we assume that we lose 2 inches of height due to a false bottom set up and include a tree fern fiber drip wall (as this is thicker than a coco panel) which is about 1 inch deep. As plantings in tanks tend to be an a mixture of tall and short plants as well as open spaces to permit viewing, an assumption that the frogs can use 100% of the first 6 inches in height will give a base line estimate of usable space (instead of estimating usable space in a varied planting). The drip wall is kept to a depth of three inches out from the surface of the drip wall and is assumed to be 100% usable by the frogs.
So, for a 20” high x 24” long x 16.5” high x 12” deep tank, deducting for the substrate and drip wall changes the numbers to the following: 14.5” high x 11” deep x 24” long. So we do not calculate out the same overlapping volume twice, the three inches from the drip wall are excluded from the bottom area calculations. So then the minimal usable area ends up being (6” (height) x 8” deep x 24” long) + (14.4” height x 3” deep x 24” long) = (1152) + (1036.8) = 2188.8 cubic inches as the conservative minimal estimate for usable space. Yet this is still significantly less than the total volume of the tank (4752 cubic inches). So when the total minimal usable estimate is applied, you get only 46% of the tank (or 9.2 gallons or 2.3 gallons per frog) as estimated usable space. In a 55 gallon tank you get (6” height x 8” deep x 48” long) + (18” height x 3” deep x 48” long) = (2304) + (2592) = 4896 cubic inches or 42.3% of the volume of the tank (or 23 gallons total or 2.1 gallon/frog).
Larger volume enclosures generally have a smaller percentage of usable space when compared to their overall volume. (When compared to their smaller counterparts) So, once again, the idea that each frog gets a minimum of 5 gallons of space breaks down as the enclosures get larger. (This is counter intuitive but true unless the enclosure's floor area increases as the height increases (some breeder tanks are an example of this).
There are significant differences between the minimal amount of available space in a simple enclosure as opposed to a complex enclosure (which is why I needed to demonstrate out the differences via the cubic inches). When considering larger tanks, the 5 gallon rule may be a place to start (although in my personal experience, it is easily possible to keep and breed some darts and many hylids in higher densities for long periods.
The reason the density works in the larger enclosures is not because each frog necessarily has more space, but rather has the illusion of more space. This is where having an idea of the minimal usable/available space comes into play with a species that is territorial and/or aggressive as it gives you an idea as to how many visual barriers, hide areas, or other refugia may be necessary to accommodate the individuals in that cage. In simple cages, multiple hide areas (often one per animal) as well as visual barriers are needed, in complex enclosures fewer visual barriers are needed as the multiple available height levels available as well as the leaf and stem structure of the plants perform this function, while hide areas may also be totally supplied by the plants.
Visual barriers consist of anything that blocks the sight path from one animal to another. This prevents excess aggression as well as allowing an animal to flee from an interaction (as well as potentially increasing the density at which the animals can be kept). Visual barriers are not important to non-territorial/nonaggressive species such as some hylids (except by providing more surface area for perching). When considering multispecies enclosures (and I am actually not talking about more than one dart frog species per enclosure), the complexity of the enclosure provides multiple niches for other species to inhabit. Species that would not do well together in a simple enclosure may do very well together in complex enclosures due to the advantages of the multiple niches provided. The additions of some thin branches to the upper areas of the tank can create an entirely new habitation zone for a different species. In general, for most multispecies enclosures, there needs to be some gradient in the enclosure to be able to support more than one species. This is more easily and visibly accomplished in the very large enclosures but there are also options available in smaller enclosures that are complexly set up.
Now on to the real heresy! The space taken up by the dart frogs is not used to determine the spatial needs of the other potential inhabitants (as long as they are not dart frogs or a species that looks/acts like a dart frog). The needs of the other specie(s), such as visual barriers and hide spots for territorial species, all apply and consideration must be given to prevent these requirements from making a habitat that is detrimental to the dart frogs (such as over-perching, basking lights causing excess temperature, etc.) The reason that the space occupied by the dart frogs is not counted against the spatial needs of the other animal is that unless the species chosen to live in the same enclosure behaves/looks like a dart frog, it will be ignored by the dart frogs (there are some other guide rules which I will bring up later). For example, if one of the sympatric Gonatodes or Sphaerodactyline geckos are chosen as the second target species, the dart frogs will ignore the lizards. However, as these are territorial to each other in their own right, the limits required by spatial needs of the lizards will curtail the number of lizards in the enclosure.
Now, this does not mean that there is an unending number of animals that can be placed in the enclosure. Generally speaking, less is more when it comes to multispecies enclosures. There is a finite number, but that number is not directly determined by the amount of space available, but instead by the availability and amount of suitable habitat(s) that the volume can contain. Obviously the smaller the tank, the fewer the habitats!
The number of niches then determines the number of species, and the territorial needs of the animal will determine the density/number of animals per enclosure (predicated on some comments to follow). In addition, it is also partially dependent on the target species chosen, the size and complexity of the enclosure, the ease of cleaning of the enclosure, and the ease of feeding the animals. In general, the smaller the cage the fewer the species. Multiple species are still possible in a small enclosure and are often set-up unintentionally as many people do not count the various invertebrate populations that are established in the enclosures (most of which are not native to the frogs areas to begin with) for janitorial and/or frog food purposes. I tend to use one species to a niche as a basic rule of thumb and that has been very workable for me.
So, in summation, in order to even begin to consider if a multiple species enclosure is an option, the following must be determined (even prior to considering parasites/disease and stress):
1) Is there more than one niche available?
2) Will the conditions available to the animals (both frogs and others) be suitable for those animals?
3) If the animal(s) are territorial, do I have enough visual barriers and hiding spots?
4) Can I easily feed, clean, and maintain the enclosure in the chosen configuration? If not, will any changes made to make the enclosure easier to maintain change the animal(s) requirements? If so, can I then meet those requirements?
5) Will the shape or behavior of one animal affect the territoriality of another animal in the enclosure?
In other words, a LOT of issues need to be considered for the setup before considering placing multiple species together. It is possible but it takes a LOT of planning and thought to do it properly, even before considering the other two main problems.
All of the information provided in this reference page has been compiled by me, but I did not write it. (Save summarization in the Q&A section). The majority was written by Ed, who is a well known and very experienced herpetologist and zookeeper. He is likely the most experienced person on this board when it comes to multispecies enclosures. Some information from other individuals has also been quoted and included in this page and is cited appropriately.
When referring to mixed enclosures, the use of the word mixed is an inapt description as this indicates that the animals are together in a homogenized fashion. Because this is not what typically happens, ‘multispecies’ is a better description of the properly set-up enclosure and will be used throughout this write-up.
Multispecies enclosures are becoming more and more common with the larger and better Zoos (including some of those at the forefront of dendrobatid breeding such as NAIB) and Aquaria. Many of the multispecies enclosures at these institutions have been present for years (some for more than a decade) with little to no problems and on some occasions house multiple generations of the animals on exhibit.
There are a lot of potential problems that get thrown whenever multispecies enclosures are brought up on various forums (not just this one). These include, among potential others:
1) The spatial requirements of the animals are violated
2) Pathogens
3) Stress
SPATIAL REQUIREMENTS:
This is an issue where some hard and fast numbers have become predominantly quoted in the hobby. Usually, people speak about 5 gallons per frog. To make this simple, I am using the assumption that the 5.5 gallon tank is the standard for the 5 gallons that is the commonly used reference.
Within the 5.5 gallons of space, the space used by the frog (I am going to use a Tinc. as a standard for the larger dart frogs) is typically very different than the space allotted. In a typically planted setup, the frog will only use the bottom of the tank most of the time. So the actual total space used by the frog can be calculated by the surface area of the bottom of the tank (8 inches by 12 inches) and, say, 3 inches of head room for the frogs to hop. A 5.5 gallon tank contains 960 cubic inches so the frogs only really use 30% (288/960 = 0.3) of the available space or about 1.65 gallons.
What this means is that people have to pay attention to how the tank is portioned out for the frogs. With the set-up described above (5.5 gallon tank) there may be between 4 to 5 inches (subtracting for bottom of the tank) of height in the tank that is not used by the dart frog. This would indicate that another species could inhabit that niche if the owner of the enclosure was so inclined. In a manner similar to aquariums, people can look at the enclosure as having an upper portion, a middle portion, and a lower portion. In most of the smaller enclosures, this will only be two levels. The other space designates a niche that can potentially be used for a different species. This is where multispecies enclosure planning begins. The person needs to be aware of how much space is really being utilized in the enclosure by the animals. This will give you the first step on the path to the next choice if you wish to keep multispecies enclosures.
To repeat, I am looking at a conservative minimal spatial availability, not the maximum the frogs can/will use (this is an important distinction). So even looking at the minimal space available to the frogs in a more complex set-up such as those that include drip walls and plants, the ratio of habitable space still decreases as the volume of the tank increases. As more and more of the volume of the tank is represented by glass and air volume there becomes less habitable space for the frog. However it is this change that creates the changes in the moisture levels, humidity, air flow patterns, and light patterns that create different microhabitats which allow additional multispecies options.
If we assume that we lose 2 inches of height due to a false bottom set up and include a tree fern fiber drip wall (as this is thicker than a coco panel) which is about 1 inch deep. As plantings in tanks tend to be an a mixture of tall and short plants as well as open spaces to permit viewing, an assumption that the frogs can use 100% of the first 6 inches in height will give a base line estimate of usable space (instead of estimating usable space in a varied planting). The drip wall is kept to a depth of three inches out from the surface of the drip wall and is assumed to be 100% usable by the frogs.
So, for a 20” high x 24” long x 16.5” high x 12” deep tank, deducting for the substrate and drip wall changes the numbers to the following: 14.5” high x 11” deep x 24” long. So we do not calculate out the same overlapping volume twice, the three inches from the drip wall are excluded from the bottom area calculations. So then the minimal usable area ends up being (6” (height) x 8” deep x 24” long) + (14.4” height x 3” deep x 24” long) = (1152) + (1036.8) = 2188.8 cubic inches as the conservative minimal estimate for usable space. Yet this is still significantly less than the total volume of the tank (4752 cubic inches). So when the total minimal usable estimate is applied, you get only 46% of the tank (or 9.2 gallons or 2.3 gallons per frog) as estimated usable space. In a 55 gallon tank you get (6” height x 8” deep x 48” long) + (18” height x 3” deep x 48” long) = (2304) + (2592) = 4896 cubic inches or 42.3% of the volume of the tank (or 23 gallons total or 2.1 gallon/frog).
Larger volume enclosures generally have a smaller percentage of usable space when compared to their overall volume. (When compared to their smaller counterparts) So, once again, the idea that each frog gets a minimum of 5 gallons of space breaks down as the enclosures get larger. (This is counter intuitive but true unless the enclosure's floor area increases as the height increases (some breeder tanks are an example of this).
There are significant differences between the minimal amount of available space in a simple enclosure as opposed to a complex enclosure (which is why I needed to demonstrate out the differences via the cubic inches). When considering larger tanks, the 5 gallon rule may be a place to start (although in my personal experience, it is easily possible to keep and breed some darts and many hylids in higher densities for long periods.
The reason the density works in the larger enclosures is not because each frog necessarily has more space, but rather has the illusion of more space. This is where having an idea of the minimal usable/available space comes into play with a species that is territorial and/or aggressive as it gives you an idea as to how many visual barriers, hide areas, or other refugia may be necessary to accommodate the individuals in that cage. In simple cages, multiple hide areas (often one per animal) as well as visual barriers are needed, in complex enclosures fewer visual barriers are needed as the multiple available height levels available as well as the leaf and stem structure of the plants perform this function, while hide areas may also be totally supplied by the plants.
Visual barriers consist of anything that blocks the sight path from one animal to another. This prevents excess aggression as well as allowing an animal to flee from an interaction (as well as potentially increasing the density at which the animals can be kept). Visual barriers are not important to non-territorial/nonaggressive species such as some hylids (except by providing more surface area for perching). When considering multispecies enclosures (and I am actually not talking about more than one dart frog species per enclosure), the complexity of the enclosure provides multiple niches for other species to inhabit. Species that would not do well together in a simple enclosure may do very well together in complex enclosures due to the advantages of the multiple niches provided. The additions of some thin branches to the upper areas of the tank can create an entirely new habitation zone for a different species. In general, for most multispecies enclosures, there needs to be some gradient in the enclosure to be able to support more than one species. This is more easily and visibly accomplished in the very large enclosures but there are also options available in smaller enclosures that are complexly set up.
Now on to the real heresy! The space taken up by the dart frogs is not used to determine the spatial needs of the other potential inhabitants (as long as they are not dart frogs or a species that looks/acts like a dart frog). The needs of the other specie(s), such as visual barriers and hide spots for territorial species, all apply and consideration must be given to prevent these requirements from making a habitat that is detrimental to the dart frogs (such as over-perching, basking lights causing excess temperature, etc.) The reason that the space occupied by the dart frogs is not counted against the spatial needs of the other animal is that unless the species chosen to live in the same enclosure behaves/looks like a dart frog, it will be ignored by the dart frogs (there are some other guide rules which I will bring up later). For example, if one of the sympatric Gonatodes or Sphaerodactyline geckos are chosen as the second target species, the dart frogs will ignore the lizards. However, as these are territorial to each other in their own right, the limits required by spatial needs of the lizards will curtail the number of lizards in the enclosure.
Now, this does not mean that there is an unending number of animals that can be placed in the enclosure. Generally speaking, less is more when it comes to multispecies enclosures. There is a finite number, but that number is not directly determined by the amount of space available, but instead by the availability and amount of suitable habitat(s) that the volume can contain. Obviously the smaller the tank, the fewer the habitats!
The number of niches then determines the number of species, and the territorial needs of the animal will determine the density/number of animals per enclosure (predicated on some comments to follow). In addition, it is also partially dependent on the target species chosen, the size and complexity of the enclosure, the ease of cleaning of the enclosure, and the ease of feeding the animals. In general, the smaller the cage the fewer the species. Multiple species are still possible in a small enclosure and are often set-up unintentionally as many people do not count the various invertebrate populations that are established in the enclosures (most of which are not native to the frogs areas to begin with) for janitorial and/or frog food purposes. I tend to use one species to a niche as a basic rule of thumb and that has been very workable for me.
So, in summation, in order to even begin to consider if a multiple species enclosure is an option, the following must be determined (even prior to considering parasites/disease and stress):
1) Is there more than one niche available?
2) Will the conditions available to the animals (both frogs and others) be suitable for those animals?
3) If the animal(s) are territorial, do I have enough visual barriers and hiding spots?
4) Can I easily feed, clean, and maintain the enclosure in the chosen configuration? If not, will any changes made to make the enclosure easier to maintain change the animal(s) requirements? If so, can I then meet those requirements?
5) Will the shape or behavior of one animal affect the territoriality of another animal in the enclosure?
In other words, a LOT of issues need to be considered for the setup before considering placing multiple species together. It is possible but it takes a LOT of planning and thought to do it properly, even before considering the other two main problems.