Purple tang in a 5x2 tank but 16" height?

[Zbutcher]

Hey everyone,

Would a purple tang do well in a tank of this size? It's 5x2 but only 16 inches tall. This tank is more of a lagoon type tank but I just want to make sure the height is okay for it full grown?

Thanks.

 

[Jay Hemdal]

IMO - that's the best configuration for tangs; lots of horizontal swimming area. That's about 100 gallons nominal capacity. Now, if you fill it up with rock and coral, that's a different story (grin).

Back in the 1970's I worked for a wholesaler who had 8' x 4' x 12" tanks - the tangs loved it, even dinner plate sized achilles....

Jay

 

[vetteguy53081]

I agree on Length being of importance. 100g would be a minimum with a 210 or similar being more ideal

 

[Zbutcher]

IMO - that's the best configuration for tangs; lots of horizontal swimming area. That's about 100 gallons nominal capacity. Now, if you fill it up with rock and coral, that's a different story (grin).

Back in the 1970's I worked for a wholesaler who had 8' x 4' x 12" tanks - the tangs loved it, even dinner plate sized achilles....

Jay

Different story in a bad way? I'm confused lol. R u saying don't fill it with corals and rocks?

Wow no kidding hey? That's reassuring

 

[Zbutcher]

I agree on Length being of importance. 100g would be a minimum with a 210 or similar being more ideal

It's going to be fairly lightly stocked so I'm not super worried.

 

[Jay Hemdal]

Different story in a bad way? I'm confused lol. R u saying don't fill it with corals and rocks?

Wow no kidding hey? That's reassuring

The tang will be fine in that size tank if everything is open, lots of swimming room. However, if you fill it with coral and rock, there is a huge decrease in the available swimming room - to make up for that, you'd need a bigger tank.

Back in 2010, I wrote up a couple of papers on swimming room for fish, here is one of them:

Estimating the Need for Swimming Space for Aquarium Fishes​

Jay Hemdal

​

A common question faced by all aquarists is “what size aquarium do I need for the fish that I want to keep?” This article will help aquarists identify potential problems in terms of acquiring a fish that may outgrow their available aquarium resources. Remember that it is always much better to answer this question for yourself before a new animal is purchased, than to have to deal with a fish that has grown too large for its aquarium.

Most aquarists understand that every aquarium has a biological “carrying capacity” – primarily the ability for the filtration system to render the waste products produced by the animals into relatively non-toxic substances. If the carrying capacity is exceeded, the result is deteriorating water quality such as dropping pH, rising nitrate levels and in extreme cases, rising ammonia and/or declining dissolved oxygen concentrations.

Aquarists also know that each aquarium has a “territorial limit” in terms of how many fish of which species, and of what size can be safely housed together before fighting becomes an issue (Hemdal 2006). In some cases, two species will simple never be compatible. In other instances, the level of compatibility will vary depending on tank decorations, relative sizes of the fish, and even the fish’s individual nature.

Once the issue of carrying capacity and territorial limit have been resolved, there is still the third question of “how much swimming room does each of the fish require in order to remain healthy?” In the past, aquarists attempted to determine this “need for swimming space” based mostly on their own experiences. New aquarists lacking this knowledge would therefore at a distinct disadvantage.

What is the result of keeping a fish in an aquarium that does not offer it enough swimming room? The biggest concern with fish in too small of an aquarium is that they may suffer chronic injury. If the fish cannot comfortably turn in the aquarium, it may bump its mouth, or eye. Done enough times, this can lead to tissue damage; rubbed snouts, bulging eyes, deformed fins, etc. If the fish is showing no detrimental signs of being housed in too small of an aquarium, is there even a problem? What about the fish’s psychological well being? The question of swimming space frequently becomes an emotional issue that cannot readily be resolved.

This article examines the need for swimming room based more on tangible measurements and less on opinion. The process begins by first determining the values for the three variables that need to be used in the calculation; tank measurement, body style of the species, and the expected adult size of the fish.

Determining the adult size of fish in captivity confounds many people, just what is the expected maximum size of our fish in captivity? Many aquarists use the Internet site www.FishBase.com for maximum size records of fish, and extrapolate captive size estimates from that data. The problem is two-fold, first the FishBase records are for maximum sizes recorded, not normal adult size - and second, many fish do not grow as large in captivity as they may in the wild. In order to test the ability of FishBase to reflect the normal maximum captive sizes of adult fish, specimens at a public aquarium were used as a comparison. The fish in the study group had reached their full captive adult size and it was found that this ranged from 45% to 91% of the maximum FishBase size for each of the species. The average was 66%. So if people are using the FishBase maximum size records to estimate how large a fish will grow in an aquarium, it is more accurate to use two thirds of that value as the captive maximum size. Aquarists wishing to be a bit more conservative in their calculations could use 80% of the stated maximum value. There are a few exceptions to this process; some small tetras, gobies, clownfish and other species that may live years longer in captivity than they would in the wild, will sometimes exceed the maximum wild sizes listed in FishBase.

The next step in the process is to determine the body style of the species of fish in question. Obviously, anglerfish utilize less swimming room than do surgeonfish. Three basic body types were selected; fish that spend at least some of their time stationary on the bottom (category 1), species used to maneuvering in and around underwater structures (category 2), and active, open water swimmers (category 3)

Category 1 Stationary Species​	Category 2 Maneuverable Swimmers​	Category 3 Open Water Swimmers​
Anglerfish	Anthias	Danios
Corydoras catfish	Cichlids (most)	Fusilers
Dwarf lionfish	Clownfish	Jacks
Eels (divide length by 3)	Damselfish	Moorish Idol
Gobies	Discus	Pangasiid catfish
Lungfish (2/3 length)	Marine angelfish or butterflyfish	Parrotfish
Pipefish (divide length by 2)	Poecilids – livebearers Cyprinids – minnows	Pelagic sharks
Seahorses (use ½ body height)	Rasboras Tetras	Rainbowfish / Atherinids
Scorpionfish	Stingrays	Surgeonfish / tangs
Suckermouth catfish	Triggerfish	Wrasses (most)

Suggested examples of fish for each of the three swimming style categories


The final of the three variables is aquarium size. Since fish typically swim in three dimensions, it was initially thought that using the aquarium’s length x height x width would work as a way to compare different aquariums. It turns out that if this is done, one actually ends up comparing aquarium volume to the linear measure of the fish and this does not work because as the fish length increases linearly, the tank volume increases by the cube, and the ratio of these numbers are meaningless. Since most aquariums have a height that is proportional to their length and width, it was decided to remove the former from the equation. Therefore, the length plus the width value is linear, and can be directly compared to fish’s length. One final factor is that many aquariums, (especially reef tanks) have many solid features which obviously reduce the available swimming room for the fish. Therefore, to obtain the proper measurement, the aquarist would take the width of the aquarium’s open water area and add it to the length of the longest open water stretch, thus not counting space taken up by decorations.

The basic equation is: Open water tank length + open water tank width / maximum fish length. This result is then expressed as a ratio. The ratio was then compared to a data set for fish from currently properly operating aquariums. For each of the three body styles, an absolute minimum and a preferred minimum ratio was determined:



Body style 1 – Sedentary fishes:

Absolute minimum ratio 1:3.5

Preferred minimum ratio 1:5



Body style 2 – Maneuverable swimmers

Absolute minimum ratio 1:5

Preferred minimum ratio 1:7



Body style 3 – Active swimmers

Absolute minimum ratio 1:8

Preferred minimum ratio 1:10


To illustrate this, take the real life example of a 10 inch long Bignose unicornfish, Naso vlamingii. FishBase lists the maximum size of this species as 23.4 inches, so multiplying that by .66 gives a predicted maximum captive size of 15.5 inches. This fish is in an aquarium that has an open water area that is 70 inches long by 50 inches wide, for a total of 120 inches. At the fish’s current size, the ratio would be 1:12, slightly above the preferred minimum ratio. If the fish grows to the predicted maximum size, the ratio drops to 1:7.8, slightly below the absolute minimum range for an active swimmer such as this species.

Bear in mind that this method only estimates the swimming space requirements for a single fish in a given aquarium. It does not calculate the biological carrying capacity, or territorial limits of an aquarium. It also does not factor in the need for increased swimming room when multiple fish are utilizing the same space. This means that if the formula suggests you can maintain a surgeonfish in a 100 gallon aquarium, it does not mean that this will necessarily be the case for even two surgeonfish to be housed in that aquarium – this information about multiple fish still needs to be determined from other sources or personal experience.

Some aquarists have suggested that this formula does not apply to very small fishes. Take the case of a one inch long zebra danio. This type 3, actively swimming fish requires a preferred minimum of open water swimming space of ten times its length – perhaps a 7” by 3” space. This strikes most home aquarists as being too small. However, this is an illusion created by personal bias – that zebra danio has proportionally just as much room to swim as a six inch long wrasse does in a 48” by 12” open water space, say a 55 gallon aquarium – which would not seem too small to most aquarists.

Readers must understand that this method gives the suggested minimum size for an aquarium needed to house a particular species, it was not designed as a way to validate aquarists trying to over-stock their aquariums or to keep fish in too small of an aquarium. It does however offer a realistic way to determine the minimum swimming space requirements of fish, and thus adds to the ability for aquarists to offer their fish the best possible captive environment in which to live, grow and reproduce. You cannot go wrong by offering your fish more swimming space than these calculations show, but fish can quickly run into trouble if they are given less swimming room.





References



Froese, R. and D. Pauly. Editors. 2010. FishBase.
World Wide Web electronic publication.
www.fishbase.org



Hemdal, J.F. 2009. Mini-Aquariums. 144p. BowTie Press, Laguna Hills, California



Hemdal 2009. For Good Measure - Calculating the Swimming Space Requirements for Fishes in Aquariums. Practical Fishkeeping Magazine. Issue 7, July, 2009



Hemdal, J.F. 2006. Advanced Marine Aquarium Techniques. 352pp. TFH publications, Neptune City, New Jersey



Mohan, P., Hemdal. J.F., and Loiselle, P. 1997. Tropical lunkers. Aquarium Fish 9(7):60-65.

 

[Zbutcher]

The tang will be fine in that size tank if everything is open, lots of swimming room. However, if you fill it with coral and rock, there is a huge decrease in the available swimming room - to make up for that, you'd need a bigger tank.

Back in 2010, I wrote up a couple of papers on swimming room for fish, here is one of them:

Estimating the Need for Swimming Space for Aquarium Fishes​

Jay Hemdal

​

A common question faced by all aquarists is “what size aquarium do I need for the fish that I want to keep?” This article will help aquarists identify potential problems in terms of acquiring a fish that may outgrow their available aquarium resources. Remember that it is always much better to answer this question for yourself before a new animal is purchased, than to have to deal with a fish that has grown too large for its aquarium.

Most aquarists understand that every aquarium has a biological “carrying capacity” – primarily the ability for the filtration system to render the waste products produced by the animals into relatively non-toxic substances. If the carrying capacity is exceeded, the result is deteriorating water quality such as dropping pH, rising nitrate levels and in extreme cases, rising ammonia and/or declining dissolved oxygen concentrations.

Aquarists also know that each aquarium has a “territorial limit” in terms of how many fish of which species, and of what size can be safely housed together before fighting becomes an issue (Hemdal 2006). In some cases, two species will simple never be compatible. In other instances, the level of compatibility will vary depending on tank decorations, relative sizes of the fish, and even the fish’s individual nature.

Once the issue of carrying capacity and territorial limit have been resolved, there is still the third question of “how much swimming room does each of the fish require in order to remain healthy?” In the past, aquarists attempted to determine this “need for swimming space” based mostly on their own experiences. New aquarists lacking this knowledge would therefore at a distinct disadvantage.

What is the result of keeping a fish in an aquarium that does not offer it enough swimming room? The biggest concern with fish in too small of an aquarium is that they may suffer chronic injury. If the fish cannot comfortably turn in the aquarium, it may bump its mouth, or eye. Done enough times, this can lead to tissue damage; rubbed snouts, bulging eyes, deformed fins, etc. If the fish is showing no detrimental signs of being housed in too small of an aquarium, is there even a problem? What about the fish’s psychological well being? The question of swimming space frequently becomes an emotional issue that cannot readily be resolved.

This article examines the need for swimming room based more on tangible measurements and less on opinion. The process begins by first determining the values for the three variables that need to be used in the calculation; tank measurement, body style of the species, and the expected adult size of the fish.

Determining the adult size of fish in captivity confounds many people, just what is the expected maximum size of our fish in captivity? Many aquarists use the Internet site www.FishBase.com for maximum size records of fish, and extrapolate captive size estimates from that data. The problem is two-fold, first the FishBase records are for maximum sizes recorded, not normal adult size - and second, many fish do not grow as large in captivity as they may in the wild. In order to test the ability of FishBase to reflect the normal maximum captive sizes of adult fish, specimens at a public aquarium were used as a comparison. The fish in the study group had reached their full captive adult size and it was found that this ranged from 45% to 91% of the maximum FishBase size for each of the species. The average was 66%. So if people are using the FishBase maximum size records to estimate how large a fish will grow in an aquarium, it is more accurate to use two thirds of that value as the captive maximum size. Aquarists wishing to be a bit more conservative in their calculations could use 80% of the stated maximum value. There are a few exceptions to this process; some small tetras, gobies, clownfish and other species that may live years longer in captivity than they would in the wild, will sometimes exceed the maximum wild sizes listed in FishBase.

The next step in the process is to determine the body style of the species of fish in question. Obviously, anglerfish utilize less swimming room than do surgeonfish. Three basic body types were selected; fish that spend at least some of their time stationary on the bottom (category 1), species used to maneuvering in and around underwater structures (category 2), and active, open water swimmers (category 3)

Category 1 Stationary Species​	Category 2 Maneuverable Swimmers​	Category 3 Open Water Swimmers​
Anglerfish	Anthias	Danios
Corydoras catfish	Cichlids (most)	Fusilers
Dwarf lionfish	Clownfish	Jacks
Eels (divide length by 3)	Damselfish	Moorish Idol
Gobies	Discus	Pangasiid catfish
Lungfish (2/3 length)	Marine angelfish or butterflyfish	Parrotfish
Pipefish (divide length by 2)	Poecilids – livebearers Cyprinids – minnows	Pelagic sharks
Seahorses (use ½ body height)	Rasboras Tetras	Rainbowfish / Atherinids
Scorpionfish	Stingrays	Surgeonfish / tangs
Suckermouth catfish	Triggerfish	Wrasses (most)

Suggested examples of fish for each of the three swimming style categories


The final of the three variables is aquarium size. Since fish typically swim in three dimensions, it was initially thought that using the aquarium’s length x height x width would work as a way to compare different aquariums. It turns out that if this is done, one actually ends up comparing aquarium volume to the linear measure of the fish and this does not work because as the fish length increases linearly, the tank volume increases by the cube, and the ratio of these numbers are meaningless. Since most aquariums have a height that is proportional to their length and width, it was decided to remove the former from the equation. Therefore, the length plus the width value is linear, and can be directly compared to fish’s length. One final factor is that many aquariums, (especially reef tanks) have many solid features which obviously reduce the available swimming room for the fish. Therefore, to obtain the proper measurement, the aquarist would take the width of the aquarium’s open water area and add it to the length of the longest open water stretch, thus not counting space taken up by decorations.

The basic equation is: Open water tank length + open water tank width / maximum fish length. This result is then expressed as a ratio. The ratio was then compared to a data set for fish from currently properly operating aquariums. For each of the three body styles, an absolute minimum and a preferred minimum ratio was determined:



Body style 1 – Sedentary fishes:

Absolute minimum ratio 1:3.5

Preferred minimum ratio 1:5



Body style 2 – Maneuverable swimmers

Absolute minimum ratio 1:5

Preferred minimum ratio 1:7



Body style 3 – Active swimmers

Absolute minimum ratio 1:8

Preferred minimum ratio 1:10


To illustrate this, take the real life example of a 10 inch long Bignose unicornfish, Naso vlamingii. FishBase lists the maximum size of this species as 23.4 inches, so multiplying that by .66 gives a predicted maximum captive size of 15.5 inches. This fish is in an aquarium that has an open water area that is 70 inches long by 50 inches wide, for a total of 120 inches. At the fish’s current size, the ratio would be 1:12, slightly above the preferred minimum ratio. If the fish grows to the predicted maximum size, the ratio drops to 1:7.8, slightly below the absolute minimum range for an active swimmer such as this species.

Bear in mind that this method only estimates the swimming space requirements for a single fish in a given aquarium. It does not calculate the biological carrying capacity, or territorial limits of an aquarium. It also does not factor in the need for increased swimming room when multiple fish are utilizing the same space. This means that if the formula suggests you can maintain a surgeonfish in a 100 gallon aquarium, it does not mean that this will necessarily be the case for even two surgeonfish to be housed in that aquarium – this information about multiple fish still needs to be determined from other sources or personal experience.

Some aquarists have suggested that this formula does not apply to very small fishes. Take the case of a one inch long zebra danio. This type 3, actively swimming fish requires a preferred minimum of open water swimming space of ten times its length – perhaps a 7” by 3” space. This strikes most home aquarists as being too small. However, this is an illusion created by personal bias – that zebra danio has proportionally just as much room to swim as a six inch long wrasse does in a 48” by 12” open water space, say a 55 gallon aquarium – which would not seem too small to most aquarists.

Readers must understand that this method gives the suggested minimum size for an aquarium needed to house a particular species, it was not designed as a way to validate aquarists trying to over-stock their aquariums or to keep fish in too small of an aquarium. It does however offer a realistic way to determine the minimum swimming space requirements of fish, and thus adds to the ability for aquarists to offer their fish the best possible captive environment in which to live, grow and reproduce. You cannot go wrong by offering your fish more swimming space than these calculations show, but fish can quickly run into trouble if they are given less swimming room.





References



Froese, R. and D. Pauly. Editors. 2010. FishBase.
World Wide Web electronic publication.
www.fishbase.org



Hemdal, J.F. 2009. Mini-Aquariums. 144p. BowTie Press, Laguna Hills, California



Hemdal 2009. For Good Measure - Calculating the Swimming Space Requirements for Fishes in Aquariums. Practical Fishkeeping Magazine. Issue 7, July, 2009



Hemdal, J.F. 2006. Advanced Marine Aquarium Techniques. 352pp. TFH publications, Neptune City, New Jersey



Mohan, P., Hemdal. J.F., and Loiselle, P. 1997. Tropical lunkers. Aquarium Fish 9(7):60-65.

Haha that's awesome. I'll give that a read here shortly. There will be rock and will be coral, however I am going to scape it in such a way that allows for many tunnels and and caveways. The main reason for this tank is to propagate corals