Clown Loaches & Hierarchy Behaviour

[Sophie]

All six of my Clown Loaches were purchased at a similar size and age, pretty much at the same time as each other.
I've had them about a year now and watched them grow, especially the alpha who is now about twice the size of the smallest one of the group, possibly larger.
I don't worry about them being boisterous with each other as there are plenty of hiding spaces for them to retreat and I know all are getting food - it's all normal so to speak.
But the smallest one to be fair is the same size as when brought, so obviously not getting as much food as the rest but enough to remain healthy and sustained.
 
My question to you guys is..
 
Now the group is fully established amongst themselves, would it better for the smaller Clowns to go with others its same size, and to replace my current group with larger ones similar to the alphas size or not?
I've heard many cases where the 'runt' of the pack can become the alpha of another group and so on, so would it be worth giving him a chance elsewhere? Or leave them happy as they are and just have several different sizes.
 

 

[TwoTankAmin]

I have a group of 5 clowns most of which I have had for 10 or more years. the largest is now a good 10-12 inces TL. the ssmalles has not grown much. It is clearly 10% or less the size of the biggest. I have two theories about this as it is not uniquie to clown loaches in my experience.
 
The first theory is simple. just like with humans some are born as "little people", they never grow to the normal human height. Why should this sort of thing also not occur to many other species as well? The difference in this for other species is that in the wild the result is the animal never makes it to adulthood. this is no different than the idea the fsh can have a heart attacj or a stroke which cause sudden deaths just as they do in humans.
 
The second theory is more complex and I have not been able to find any scientific literature which discusses it. Having had spawning fish in my tanks almost from day one. I started to observe a phemomenon. In any group of growing fry there develops a competition for food. The fastest, boldest and strongest get the food first. Some fish will "fight" for their share, other will be bullied into waiting and not eating as much. As the fry grow this competition gets more intense and is usually accompanied by the typical pecking order establishment common in many groups of fish. The fish see each other as competing for food etc. the weaker fish usually get killed or driven off. In tanks driven off is often not a possibility.
 
I would move baby bristlenose plecos into growout tanks. The fish all started at similar sizes, but very soon most were clearly bigger, but a few seemed to lag in growth. I have noticed this in other fish as well. As the fish grew to a size where they could be sold, my prctivce was and is to send out the largest anbd healthiest fish first. And as the numbers in the grow tank dwindled what remained were the smallest fish. But what happened next was interesting. With the removal of the larger fish, the smaller ones began to grow rapidly and soon had caught up with the norm.
 
Here is what I believe I saw. As a way to avoid being beaten up and harassed some of the fish developed a strategy of intentionally keeping themselves small. They seemed to make an active choice not to compete violently. The result is the stayed much smaller than their peers. Somehow I have come to interpret this as an intentional strategy. By keeping themselves smaller than the other, the fish become less perceived as competition. But when the big guys are gone, the ones who have kept themselves little start to grow because they now get ore food easily and don't get attacked.
 
But here is the most interesting thing I observed from my group of clowns. Incidentally I have come to believe my small guy is a 'dwarf". As the group worked out its pecking order there were heroic running battles between the two largest. But there were also battles between the rest. A pecking order has to be all the way from the top to the bottom. But when one of the middle sized clowns, which clearly had no chance to be number one, would start to pick in the little guy, the big one would come to its defense. This absolutely amazed me. What was just as neat was to see how eventually all the bigger ones would tolerate some shenanigans from the little one. Behavior by the little guy with the largest was tolerated where the same behavior for a larger one toward the big would have elicited a violent response. Even though the fish were similar ages, the 'dwarf" was treated more like a child than an adult competitor.
 
Let me leave you with this link to a photo from loaches.com. It is the reason why I have kept clowns for over a decade now. Hopefully is also helps to answer your Q, Sophie. The fish belong to Bob Darnell as does the picture http/www.loaches.com/species-index/photos/c/chromobotia_macracanthus_group04.jpg/image_view_fullscreen

 

[Sophie]

Oh they are gorgeous!
I guess mine shall stay as they are
They certainly are an amazing fish.

 

[Baccus]

I have to agree with TwoTankAmin about the varying sizes of BN fry. It probably happens with my guppies too but is harder to see on an individual scale since there are so many guppies.
My theory for the smaller fish is that the larger ones, even adult fish are releasing growth slowing hormones into the water, thus effectively keeping the smaller fry as Juvi's preventing them in theory in the wild from being able to compete so well for food, while remaining handy snack size for predators while the larger fry can scoff food and grow quicker.
It never ceases to amaze me when I am able to remove 20 odd BN fry that have finally reached 4cm to sell, how quickly the remaining fry rocket up. But the interesting thing with this is that its not all of the fry rocketing up at once. It seems that once a certain number say 30 have had the fastest growth spurt then the remaining 100 or so again slow down in their growth, until once again the largest ones are caught out again and moved. This process of fast and quick growth continues right up until all the fry are gone.
The other reason I suspect that the growth rates are hormone induced/ restricted is because when ever I need to catch out the fry that are going to the pet shop, their grow out tank gets a HUGE water change, effectively removing all of the inhibitor hormones (much like a natural flooding cleanse of a river system), and then within a couple of weeks the hormones for growth inhibitors has been able to get up to high levels again effectively putting the fish back onto grow slow mode.