STUPID question/theory

[inatthedeepend]

Hi,

I recently introduced (on a temporary basis) a Sailfin pleco to the tank of a Bristlenose pleco - and they seem to get on well enough, despite Sailfins being generally territorial - but I am a little confused about something.

As far as I was aware, Sailfin plecos will produce a hormone that stimulates the growth of the emitter fish, but will restrict the growth of other fish that come into contact with it. What I can state is that having been away for a fortnight, returning to my pleco tank I am confused as both fish have put on significant mass. Whilst the difference in the Sailfin is the most significant (the fish would appear to be roughly an inch longer - significant for a fish that was originally two inches long), the Bristlenose has grown significantly in terms of body mass, showing a dramatic thickening, which given the lack of protruding growths is in line with this fish being a female.

In terms of environment - the (temporary) tank is approx 55 litres, heated to 26 degrees by a 50w heater, lit for 12 hours a day. For the past 13 days the only food has been in the form of a holiday block. There are two pieces of bogwood. The filtration is supplied by an old Fluval 3 plus (recent phased change of both carbon foam pads) and the base of the tank has a covering of approx 25mm of gravel, there are some pieces of sedimentary rock. I have moss balls, mini amazon swords, elodiae densa (apologies for the spelling) and some form of thin long bladed leaf plant that spreads a lot by throwing out roots and popping out a new mini plant.

I apologise that I'm unable to provide empirical measurements for my observations - I never expected to see this. I also wish I knew a little more about the plants as well!

Is it possible that the release of hormone from the Sailfin has a complementary effect on the growth of the Bristlenose - or that the hormonic release from each fish complements the other? Any comments/counter theories/related experiences gratefully received. I'd like to understand this.

[racoll]

As far as I was aware, Sailfin plecos will produce a hormone that stimulates the growth of the emitter fish, but will restrict the growth of other fish that come into contact with it

Never heard of this. Where did you read it?

[TohokuChris]

I would also like to know more about the hormone theory in Sailfins. My own observations may concur:
For about two/three years now, I have raised a pair of albino sailfins in a tall 125gal well filtered tank shared with large severums and decorated with wood and clay pots. The severums occassionally spawn and all the fish have grown considerably during this time.
Both sailfins were the same size when I bought them; the standard pet-shop 6 cm or so. Since then, one of the fish has grown to the expected size (30cm) while the other has been stunted all along. The smaller has grown, but only to 15cm.
Both fish are observed to feed eagerly, and I have never observed any fighting. Actually, they seem to ignore each other. There are more than enough hiding places and both fish are regularly observed on the front glass. The severums also ignore them. I had always assumed that the smaller was just a runt?
Again, I'd be keen to read any more about this phenomonon, and does it extend to other species?

[Silurus]

There is an entire body of literature (fisheries-related, of course) on stress and growth suppression in fishes. The physiological mechanisms are more mundane and nothing like you described.

[Bas Pels]

As Silurius wrote, fish growth can be limited due to stress, and keeping 2 fishes of a species (this goes for any species) will almost always result in o1 being stronger, and therefore dominant over the other.

The result is generally that out of any combination of 2 conspecefics 1 will grow nicely and the other not

In 2004 I started with 6 gibbiceps in my 4 meter - 13 feet - tank @ ~6 cm. after a year they all measured ~17 cm, and after another year around 30 cm

The difference with Chris is that my group was significantly larger - thus no fish could dominate the others, and the tank (2800 l in stead of 500) was larger too, with much more hiding places. In fact, I have hardly seen them in the first year.

I think that made the evenly growth possible: group size and tank size

[inatthedeepend]

I may regret this next sentence...

I was told about the hormone emission by the retailer at the local aquarium shop.

With hindsight, this is the same chap who told me a Sailfin would grow to 12".

[Bas Pels]

a very knowledgeble chap

[Barbie]

So now the question is truly, what did you learn? ;)

Barbie

[inatthedeepend]

What I have learnt:

1) The purpose of the local fish store is to sell fish.
2) With regards to important questions concerning specialist fish, speak to a specialist or consult a reference guide
3) I wish I understood catfish better, and I'm going to start with the two species I have!

[Barbie]

I was actually teasing ;). I own an LFS and I get quite a bit of heat because I do not let people take home incompatible species. It frustrates people that want to be free to make their own mistakes, but is appreciated by enough that I can keep my doors open. If you find an LFS like that, stay with it, and recognize that keeping those doors open to provide you with that service is not free. In the mean time, you can be free to tell the guy with the bad advice that he is full of it and should bother to educate himself if he's going to recommend things. Better yet, call his boss and tell them.

Barbie

[inatthedeepend]

He owns the store

On the plus side I've rehomed all my fish in a Fluval Roma 125, external fluval 405 filter and water set to 23 degrees - they all seem happy. I've got a fluval profile 1000 waiting for me to commission it with an aquamanta efx 1500 that will house the leopard pleco plus some appropriate tankmates.

Both placos seem to be competing to be the biggest catfish - I'm quite happy with this, but feel sorry for the female bristlenose - she's going to lose in the long term

[Nabobmob1]

I may be totally out of the park but I believe he's referring to a hormone supposedly released that will stunt the surrounding fish. I've seen these claims with Angel and Discus breeders that the larger dominate juvies release a hormone that stunts the growth of the smaller young. and read to increase water changes to dilute this hormone. I've never however heard of it in plecos, nor have I heard of it affecting another species.

Personally I don't believe you can change too much water on a grow out tank, however I'm not sure if any of these hormone claims are legit or simply the results of poor water quality and only the strong survive.

[inatthedeepend]

Well the growth spurts have continued, rather dramatically. The leopard plec has now matched the size of the bristlenose, and she has grown radically as well. Leading up to the new tank setup I couldn't resist a new addition to the tank - a male bristlenose. I know it's stupid to think of a fish having "company", but still. When the Leopard pleco moves on I'm going to rehome the goldfish and encourage the pair to breed come September.

In this particular case I'm inclined to disagree with the survival of the fittest theory. Water quality is crystal clear, and I've planted the tank fairly heavily with hardy species able to cope with harvesting of aufwuchs/goldfish nibbling. The only time I'm not happy with the water quality is when the cucumber I put in the tank gets mutilated, and little bits go everywhere! The fish are all extremely happy and active, feeding (and pooping) well.

The recently added bristlenose male is either mature or near mature - 5 inches ish with defined protuberances, so I'm unlikely to see much in the way of growth here, but I'll see how the leopard pleco and the female bristlenose continue to develop. Although there are products to help with tank cycling I'm planning on a month of cycling to allow plants to bed and a healthy filtration setup to mature, so they'll be tankmates for another six weeks.

[Marine590622]

I was actually teasing ;). I own an LFS and I get quite a bit of heat because I do not let people take home incompatible species. It frustrates people that want to be free to make their own mistakes, but is appreciated by enough that I can keep my doors open. If you find an LFS like that, stay with it, and recognize that keeping those doors open to provide you with that service is not free. In the mean time, you can be free to tell the guy with the bad advice that he is full of it and should bother to educate himself if he's going to recommend things. Better yet, call his boss and tell them.

Barbie

I once was questioned by a store employee about a fish purchase I was making. She asked me what size tank I was going to put the fish in and I told her it would be going into a 20. She started to refuse to sell me the fish and I explained to her that the 20 was my quarantine tank, that the fish would then move to a 10 to grow for a while. Once it had enough mas to move in with the big boys in the 120 I would move it there, I was actually impressed that they were trying to do well by the fish. 5 minutes latter I heard her tell a customer that neons and angels would make good tank mates as they come from the same river systems. Oh well...