Estimating the Need for Swimming Space for Aquarium Fishes

[JumboShrimp]

Just a general thought-- sometimes even if your fish don't go up high on a regular basis, in times of aggression one will often take advantage of the extra head-room (above the rocks) to zoom up and out of the danger posed by another fish.

 

[Premium]

Jay thank you for this incredible article. I replied to you on a separate thread asking questions before coming across your article. This sort of information is well thought out and provides an actual quantifiable determination of needed space for specific species of fish as well as understanding the how's and why's. Priceless information buddy. Thank you for all your hard work and for furthering the knowledge of this particular Reefer!

 

[Dburr1014]

Old writing but good to understand the needs.

Question: why is there such a disparity between sizes?

I looked up a purple tang, 36 cm record, 10 cm common. What?
Which number is used x 0.8 for the calculation? 14 inches seems way big and 4 inches seems to be still a juvenile.

 

[Jay Hemdal]

Old writing but good to understand the needs.

Question: why is there such a disparity between sizes?

I looked up a purple tang, 36 cm record, 10 cm common. What?
Which number is used x 0.8 for the calculation? 14 inches seems way big and 4 inches seems to be still a juvenile.

You need to be careful using Fishbase data - some of it is computer generated, and there is little human error checking. In other cases, they have some outlying record in their database (often a super male) that skews the record size. You’ll see that in some wrasses and tangs.

The 0.8 multiplier (80%) of the adult Fishbase size is from a study I did where I measured a large group of decades old fish in a public aquarium (fully grown) to the full size given in Fishbase, and those ran, on average, 80% of the Fishbase value. If you want to be more conservative, just use the raw Fishbase value.

Jay

 

[Daniel@R2R]

This is helpful!

 

[BillFish Coral Lover]

I had a standard 120 for many years, and am starting a custom 75 now, and have been concerned about this very issue. I’ll definitely be using your expertise as outlined herein. Thank you for your contributions to the hobby, Jay.

 

[sc50964]

I guess my 560G with a length of 9’ and a width of 4’ is not enough for my Dussumieri tang to live out its lifespan.

 

[BillFish Coral Lover]

Now that’s a fish!

 

[Daniel@R2R]

I guess my 560G with a length of 9’ and a width of 4’ is not enough for my Dussumieri tang to live out its lifespan.

Based on Jay's method, I'm coming up with a ratio of 1:9.17, so it should be fine.

 

[AydenLincoln]

I guess my 560G with a length of 9’ and a width of 4’ is not enough for my Dussumieri tang to live out its lifespan.

A few small sharks and rays could happily live in that tank size too lol! THAT’S A MASSIVE TANK!

 

[sc50964]

Based on Jay's method, I'm coming up with a ratio of 1:9.17, so it should be fine.

He is over 20” now…., As he grew in that tank, I started losing fish over the past 8 years. I think Jay’s number has merits.

 

[Jay Hemdal]

I guess my 560G with a length of 9’ and a width of 4’ is not enough for my Dussumieri tang to live out its lifespan.

Your tang is much larger than the record size for that species. In those cases, I would urge people to use the actual length of the fish, and not the Fishbase data. You can also use actual length if you just want to check if a tank will work temporarily for a given fish.

I wonder - are you accounting for the 30% magnification of the water when you measure your fish, or was it an out of water measurement?

Fishbase gives a maximum adult size of 16.8" That would result in a ratio of 9.2, a bit under the 10 I suggest. However, the problem is that Fishbase also gives a *normal* adult size for this species of 11.2" and that is the number you ought to use. That gives a ratio of 13.9 which is fine.

In an earlier reply to this thread, I had mentioned why you need to be careful with the Fishbase data:

You need to be careful using Fishbase data - some of it is computer generated, and there is little human error checking. In other cases, they have some outlying record in their database (often a super male) that skews the record size. You’ll see that in some wrasses and tangs.


Jay