FishBase maximum sizes- How accurate?

[Zionas]

For those of you who check FishBase for the sizes of fish, how accurate do you find their maximum sizes to be? For example on there it says a Purple Tang can get to 36.0cm (14.5 inches) and Powder Blue to about the same, Scopas to 40cm (16 inches).

Should I take their maximum size estimates seriously? Do they have it as a measure of how big most / all specimens of that species are expected to grow, or simply the largest one ever caught, or the upper end of average?

Some also list the “Common Length” or “Standard Length”, not sure what those mean but if I get a fish should I expect it to grow more to the SL / CL over the maximum size?

For example YT grows to 8” according to most sources including FishBase but I don’t think I’ve seen anyone post about a YT larger than 7” and not even sure if that’s on the big side. It says for the Yellowtail Blue Damsels and Azure / other smaller Chrysiptera they get to 7cm (2.75”) maximum but from what I’ve seen most remain at 1.5-2”.


I mean if we go by FishBase, Purple and Scopas would need 300+ gallon tanks that are at least 8’ if not 10’.

Or maybe it’s like humans where say the tallest person in a group of people is 7ft tall but then you’d expect the average person (at least men) to be between 5’7 and 6’0 or 6’1?

 

[Zionas]

FishBase also says Flame Angels get to 6”.

 

[Zionas]

Bump, would appreciate insights. X1

 

[mort]

Fishbase lists the maximum size of a powderblue at 54cm and the tl (total length of fish from tip of the nose to the tip of the tail fin, ie the longest a fish can measure) as 19cm. So basically the biggest ever pb measured was 54cm but the average fish only gets to about 19cm.

For a scopas it says 40cm sl, this is a maximum length only and no average length is supplied, so it's the potential maximum size not what is likely to be achieved by the average fish. Sl stands for standard length and it's basically the length from the tip of the snout to the last vertebrae, or the length of the body without the tail (this is used because some fish have streamers that would make the fish really long when in reality it isn't that big).

Common length is the average size the fish was when they were sampled, ie the average size of the fish in the population. This is a good indication of how big the fish will be in the wild as it discounts the largest and smallest.

 

[mort]

I'll just add since I missed the purple tang, average size was 19cm so they won't get much bigger than this on average but have the potential to reach 36 cm, or at least one did.

With tangs I don't think the total length is the only thing to consider when thinking of appropriate tank sizes. They might not grow to their theoretical potential but it's best to assume that they can get fairly large and should be given enough space, so if it maxes out at 5" instead of 7" it is still better to assume it could get to 7 when considering it. This is why for most species the average sizes sellers list are reasonable approximations to go by.

 

[ca1ore]

I’ve kept three purple tangs over long duration. Current one is 7 years under my care. None of them have exceeded 7”. Current one is only about 5 1/2”. Similar experience with most tangs.

 

[Zionas]

Ahhh ok where can I find the average sizes on FishBase?

 

[ReefBeta]

The yellow tang you find in the ocean can easily go bigger than a DVD. Big tangs like achilles are longer than my forearm. I have yet to see them get nearly as big in captivity.

 

[Zionas]

What’s the biggest specimen for each species of Tang that you’ve seen in captivity and how old were they?

 

[mort]

Ahhh ok where can I find the average sizes on FishBase?

I don't think you can. The reason every fish seems to have a different system of sizing is because they have collated infomation from scientific studies who used particular systems to collect the infomation.

 

[Zionas]

I see. Would you say we should generally use 75-80% as a good measure of how big the fish will get for the average specimen?

 

[Doctorgori]

I’ve seen Blue tangs on cruise that were eating size, but mine in a 210 is only 7” long after 2yrs....
every time I’ve checked Fish base I think they list max collected size not avg captive size.
I also think people grossly overstock tanks and stunt the fish, thats not a soapbox statement but more factual observation over 40yrs

 

[Zionas]

Overstocking is not something I’d like to do. What would you expect to be the average captive size of a Foxface, Yellow / Purple / Scopas Tang? From your experience.

Would you expect your Blue Tang to get anything close to a foot? I’d say 2 years and 7 inches is a fast grower eh.

 

[Doctorgori]

Overstocking is not something I’d like to do. What would you expect to be the average captive size of a Foxface, Yellow / Purple / Scopas Tang? From your experience.

Would you expect your Blue Tang to get anything close to a foot? I’d say 2 years and 7 inches is a fast grower eh.

That Atlantic Blue tang is EASILY the fastest growing tang I’ve had...I still got the receipt from Live Aquaria, but yeah it was maybe 3” when purchased, if that big ...
No clue how big it will eventually get. The ones I saw in the Carribean were like 10” but I’ll defer to fishbase as this is a guesstimate.
Fox faces grow relatively fast also, mine is about 7” also and 3yrs old
I’m gonna say 8” is the biggest foxface I’ve seen
I’ll repost pics of both when my tank lights come on at 9a ....

 

[Zionas]

Another member on here who went diving in the Caribbean also saw 10” or larger Atlantic Blue Tangs. Bob Fenner however considers them one of the Acanthurus “suitable for modest sized captive systems.” Inaccuracy on his part? Not that I’m interested in one.

 

[mort]

I see. Would you say we should generally use 75-80% as a good measure of how big the fish will get for the average specimen?

Yes that's a good rule. Fishbase is for wild fish, they don't list anything to do with aquariums.

I spoke to a expert once and they said a rough general rule for tangs is that they grow 85% of their potential size in the first 15% of their life. That basically means they grow fast when they are young and slow down massively when they get big. I'd say from my experience this is definitely true.
This "rule" however was with wild fish populations and with our aquarium kept fish there are more factors to consider. I had a regal tang grow from just over an inch to six inches plus, in a little over a year. This was with very heavy feeding in a 8ft shop display tank. In a heavily stocked tank with lots of competition for food and space, you are unlikely to see such growth.

 

[Zionas]

I see. However will this reduction in growth lead to diseases and shortened lifespans etc?

 

[mort]

Stunting is definitely a thing and arguably leads to a shortened lifespan. It's hard to say with other aspects as very few fish live anything like their maximum potential in tanks, with diseases, systems failures and other creative mortalities coming into play.

 

[Zionas]

I see. I guess best we can do is to give our creatures the best care possible. I’d be very happy to have my fish live into their teens and beyond. How old are your larger fish and how big are they?

 

[mort]

I see. I guess best we can do is to give our creatures the best care possible. I’d be very happy to have my fish live into their teens and beyond. How old are your larger fish and how big are they?

I don't really have that many fish as I haven't bought any for years now. Most of mine came from fish that simply didn't sell in the shop or were rescues. My tank has been a bit like a rehoming centre with the waif and strays with a few of my own bred fish thrown in.
For instance I have a magnificent foxface that someone bought in so skinny you could see through it. The poor thing was riddled in ws and couldn't stay upright. I spent a lot of time on bringing it back and it's now a 8" fatty.

In terms of longevity, like most of us I've had fish live a very long time but also had the odd one mysteriously die at barely any age at all. I do have some very long lived tropical fish however, with clown loaches, various catfish like a Doradid and synodontis, Bala shark, silver dollars and a few others that are between 25 and 30 years old now, plus most of the fish in my pond are well over 10 and some in their upper 20s. It simply comes down to looking after them properly, feeding them well and a little luck. I wouldn't over think it really as death is a natural part of the hobby and as long as you give them your best life that all that matters.