Slow growth rate for tangs

[mattsilvester]

Hi All,

Something that has been a problem for me for some time now has been the growth rate of my tangs. Maybe it is just me, but they seem to grow very slowly in my tank, and I could never discover why. I have a yellow tang, purple tang, blonde naso tang and powder blue tang. They share my 240 gal (8x2x2) tank with an emporer angel.

In the 30 months or so since this tank has been running, the angel has grown from 3" to 7.5", and has transformed into almost full adult colours. But my yellow and purple tangs, which has been there for at least 24 months have barely grown at all, from about 3" to about 4". Similarly, the powder blue and naso tangs, which have been there for maybe 18 months or so have grown by about an inch also...... the powder blue is now about 4-5" and the naso about 5-6".

I feed a varied diet, including a sheet of nori at least 5 days a week, a selection of frozen foods, and pelleted foods. There is no bullying, never so much as a split fin, or a fin flaring tail slapping incident...... I am trying to track down a supplier for a new pelleted type food (can't remember the name right now).... but aside from that, I can never figure out why they grow so slowly...... or does this sound normal???

Many thanks,

[ALH]

idk, but my lieutenant tang is the slowest growing fish in my tank

[pIankton]

I'd like to know as well... I've had my sailfin tang for about 2-1/2 - 3 years and it seems like it's only grown about an inch or 2 max...

[tydtran]

I wonder about this too. My yellow tang I have had since August 2006. Bought at 2 in., he is now 4 in. Regular diet of Nori, mysis, clams, shrimp, squid, mussels. He eats like a pig.

[cccapt]

I've had my c.binotatus about 3 yrs. It was about 3" when I got it, now it's maybe 5. I got my a.coeruleus about 1 yr ago. It was about 4" when I got it, now it's about 5.5. It's a little bigger than the bristletooth already, so it's growing faster.

[McSassy]

Perhaps they grow slower and not to their max size in captivity because they can easily outgrow their environment otherwise.

[mattsilvester]

It would seem tangs grow pretty slowly then...... in general..... I had a regal (hippo) tang about 10 years ago that grew from 2" to 8" in less than 2 years..... but all the other tangs I've had grew very slowly......

I had hoped they'd grow quicker to be honest :(

[tcmfish]

Tank size, water changes, and food.

[reefergeorge]

I'd like to know as well... I've had my sailfin tang for about 2-1/2 - 3 years and it seems like it's only grown about an inch or 2 max...


My sailfin grew from 3" to 6" in about two years, but slowed down drastically once he hit the 5" mark.

[MazdaSPD3]

My orangeshoulder went from 3in to 6in in roughly 14months.
My naso went from 3in to a whopping 4in in that very same time frame.

What I've noticed between the two is the orangeshoulder CONSTANTLY eats (algae on the rocks, on the barebottom floor, on a clip, and heck even coraline algae). My naso on the other hand pretty much eats whenever I feed (once, maybe twice a day), and very very rarely, from the rocks.

The crazy thing is my naso is plump and happy as far as I can tell.

[yukonblizzard]

My yellow tang has not grown at all in about a year and a half, my hippo tang has grown about 2 inches in 2 years, while my vlamingii tangs have grown extremely fast, as well as my sailfin that has grown about 5 inches in 2years.

[rort]

My unicorn and chocolate tang have grown so little over the last year I have had them. I feed heavily of dried, nori, mysis, and many other combos of food.

my foxface has grown a lot more than these two...

[mattsilvester]

......The crazy thing is my naso is plump and happy as far as I can tell.

Same thing with mine, all of my tangs for that matter..... they are all plump and happy.... no disease, no bullying, all always out and about and active.... feeding well...... just slow growers it seems..... at least slow in the context of home aquariums.

Water changes..... well admitedly for the past few months I have let things slip, but in the 2 years or so preceeding that, I used about 10 buckets of salt which is 2000 gallons or so.... which averages at 25 to 30% per month...... I know that is not what you would call massive water changes, but my tank is not exaclty heavily stocked either with less than 30" of fish in it (its an 8x2x2 240).

[tcmfish]

More water changes = more growth. This is goes with tank size if there is one fish in a huge tank and a bunch in a small tank the one in the large tank will grow faster.

Also they need food, lots of it to grow. But when I say water changes it is because fish release hormones into the water that when present will stunt the growth. So if you are constantly pumping in new water and draining the old it would simulate being in a huge tank, and with enough food the fish would grow larger than they would if being fed the same amount in the same tank with no water changes. But in the wild tangs graze all day long and sometimes that isn't beneficial to our water quality so they probably will never reach the same size they do in the wild, but they will grow fast.

[mattsilvester]

More water changes = more growth. This is goes with tank size if there is one fish in a huge tank and a bunch in a small tank the one in the large tank will grow faster.

Also they need food, lots of it to grow. But when I say water changes it is because fish release hormones into the water that when present will stunt the growth. So if you are constantly pumping in new water and draining the old it would simulate being in a huge tank, and with enough food the fish would grow larger than they would if being fed the same amount in the same tank with no water changes. But in the wild tangs graze all day long and sometimes that isn't beneficial to our water quality so they probably will never reach the same size they do in the wild, but they will grow fast.

Tim,

I was aware of that as applied to fresh water fish - especially south american chiclids et al. where populations are frequently stranded during the dry season, hence natural inhibitors are released to restrict growth. It was my understanding that marine fish essentially didn't do that, because the vast volume of the ocean would mean its a useless "tool" for nature to employ...... I would be very interested to read more on this - do you know where I could investigate same further?

It was my understanding that in as much as growth is related to food, it is realted to overall health...... i.e. if a fish is under stress, it will be unhealthy, and thus will devote more resources to maintenance and repair, and less to actual growth, in order to maintain health. Bigger tank + water changes = better water quality and better environemnt = less stress = healthier fish = better growth.......

Seriosuly considering getting some cheap salt (since my tank is FO now) and doing lots of water changes, and getting some pellet food in an auto feeder to feed every hour.......

[tcmfish]

Matt I don't have any sources for you right now. But I am going to do some research on it for you. But IIFC it is the presence of a certain hormone or waste product that inhibits the growth of the fish. Dilution in large tanks or removal by water changes increases the growth.

I am convinced you would see results if you did more water changes and fed more high quality food.

I will try and find some sources on this happening with marine fish.

[mattsilvester]

it is the presence of a certain hormone or waste product that inhibits the growth of the fish.

As I say, I am familiar of this with respect to fresh water species. It is a natural response that slows the growth of fish, temporarily, to allow greater numbers to survive on limited resourses. i.e. when flood plains dry up, isolated lakes and ponds are formed, concentrating the fish in one spot..... so if they all stay small, it means resources last longer, and once the floods return, diluting the hormones, the growth can continue.

Dilution in large tanks or removal by water changes increases the growth.

It was my understanding that in the case of marine fish, there is no natural mechanism for this to occur. i.e. the fish do not give out the growth inhibiting hormone. The logic being that marine fish don't get stranded in isolated pools, so there would be no point in releasing growth inhibiting hormones that will just get washed away in the tide.......

I am convinced you would see results if you did more water changes and fed more high quality food.

I am convinced also..... better quality foods (although I think I feed a reasonably good quality diet at present) will always help, and I think the water changes will reduce nitrates and all that, improving oxygen levels and pH stability, and so on...... and as a result of better conditions, the fish will be healthier, and will growth quicker.....

I will try and find some sources on this happening with marine fish.

I would be extremely interested in this. I have discussed this before (where and when I don't recall) - and coming from a freshwater chiclid background it is a familiar concept. As I say, I just thought it didn't apply to marine fish. I am not saying you are worng or anything like that, I am just eager to discus, and to learn more on the matter :D

In the interim, I am stepping up my water change schedule in a big way, in a bid to get nitrates down to below 10ppm, and keep them there. My tank seems to hover on the 50ppm, which I am not comfortable with...... I am hoping that a strong water change regime will give the system the boost it needs to start pushing the nitrates back, and hopefully I will be able to keep them at bay at 10ppm or less there after. Nitrates in themself are not of huge concern to me, I just use them as a barometer or water quality in general...... i.e. a well managed system will typically have low nitrates, which is a reflection of low organics, stable pH, and high oxygen levels.

Glad to discuss, and look forward to more ;)