Moonlight Gouramis And Tiger Barbs

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Lanzuis

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Hello everyone - I am fairly new to the fishkeeping hobby and I have kept them for about 5 months so please excuse my naivity! ^_^

Today I went to my LFS and a pair of Moonlight Gouramis caught my eye, I have a 90Gallon tank and so I thought it would be alright - I had 4 Tiger Barbs but I bought another 6 to limit aggression - but I don't think this has been the case as my larger barbs have been picking on the gouramis and nipping their fins - I don't know if this is to do with them being new additions or not and if it will pass and that is why I am here - will it be alright to keep them in the tank?

Thanks!
 
No, this combination will almost never work.  Please separate them (which probably means returning the gourami) because if allowed to continue the gourami will be so stressed they will develop health problems and likely die prematurely and perhaps fairly soon.
 
The Tiger Barb is a species that is prone to fin nipping.  As a species, it may calm down a bit within its own if the numbers are 8 but preferably 10 or more Tiger Barbs.  This deals with the fish itself.  But other species that are slow sedate fish, or those with long fins, should never be combined in the tank with Tiger Barbs as that is just too much of a temptation.
 
Byron.
 
I agree with Byron.

If you only have the tiger barbs in the tank, I would just get a bunch of tiger barbs. They make an excellent candidate for a species tank as they are active and fun to watch and you really ought to keep them in higher numbers anyway. You could do a mix of the colors (albino, green, regular) for extra color. Most centerpiece fish are slower movers, like the gourami, so a species tank with tigers is really a cool option. I would do more than thirty tiger barbs if you were to do a species tank.
 
attibones said:
I agree with Byron.
If you only have the tiger barbs in the tank, I would just get a bunch of tiger barbs. They make an excellent candidate for a species tank as they are active and fun to watch and you really ought to keep them in higher numbers anyway. You could do a mix of the colors (albino, green, regular) for extra color. Most centerpiece fish are slower movers, like the gourami, so a species tank with tigers is really a cool option. I would do more than thirty tiger barbs if you were to do a species tank.
  
Byron said:
No, this combination will almost never work.  Please separate them (which probably means returning the gourami) because if allowed to continue the gourami will be so stressed they will develop health problems and likely die prematurely and perhaps fairly soon.
 
The Tiger Barb is a species that is prone to fin nipping.  As a species, it may calm down a bit within its own if the numbers are 8 but preferably 10 or more Tiger Barbs.  This deals with the fish itself.  But other species that are slow sedate fish, or those with long fins, should never be combined in the tank with Tiger Barbs as that is just too much of a temptation.
 
Byron.

Thank you very much both of you - I have found that my barbs have calmed down and are keeping all of their aggression to themselves as my gouramis have settled in with the tank they are not getting nipped by any of the barbs although I am still concerned given what you have told me. I shall continue to observe them over the next week and if there fins are nipped then I shall move them into another tank.

Thanks again! :)
 
Ok, after some close observation over the day I have found that these barbs rarely make a full on effort to nip the fins of the gouramis, but they will sometimes, when passing, try and nip them. They also make attempts to chase the gouramis but never fast, very often they are slow and only make half hearted attempts.

This attempt at nipping can occur once a minute - 5 minutes and appears to be fairly 'slowly' and very little of it looks aggressive. The fish do not APPEAR to be stressed but I don't really know. It's fairly touch and go and I'd appreciate all help I can get :)
 
I didn't go into much detail previously, but I will now as you have asked.
 
There is much more going on than what little we can see.  I'll explain stress a bit more in a moment, but here let me point out the cause, and this is not only the physical aspect (chasing and nipping) but also the unseen chemical aspect.  Fish release chemical signals into the water, what we term pheromones and allomones.  One reason we do regular partial water changes is to remove these, as they cannot be "filtered" out by any means, and they can have dangers.  Pheromones are picked up by others in the species, and these chemicals are used to initiate spawning, avoid danger, warn off others of the species, emphasize dominance or submission, warn of aggression, and so forth.  Fish use this chemical stimuli something akin to how terrestrial animals use sounds.  Birds for instance are now known to have incredible vocabularies and they can actually communicate similarly to our conversation with each other.  But back to fish, the allomones are the real danger here, as these chemical signals are sent out by a fish to be read by other species.  These are primarily aggressive in nature, to warn other fish, protect a territory, etc.  A rather good comparison can be made by considering a vicious dog chained to the wall in a closed room, into which a cat has been tossed.  The cat will be severely frightened by the mere presence of the dog and its behaviours, and even though no physical contact occurs because the dog is prevented by the chain, the effect on the cat is catastrophic because the cat does not know it is "safe" but only knows what it reads from the dog's signals.  If you have ever been bullied, you will understand what this can do even in the absence of physical contact.  Same holds for these fish.
 
Subjecting fish like the gourami to the presence of a species like the Tiger Barb will be detrimental and this can increase.  These things cause stress, and this is the major cause of fish disease.  I researched this topic extensively for an article a couple of years back, so I will cut and paste some of that here.
 
Biology Online defines stress:
 
The sum of the biological reactions to any adverse stimulus—physical, mental or emotional, internal or external—that tends to disturb the organisms homeostasis; should these compensating reactions be inadequate or inappropriate, they may lead to disorders.
 
Homeostasis is defined as “the tendency of an organism or a cell to regulate its internal conditions, usually by a system of feedback controls, so as to stabilize health and functioning, regardless of the outside changing conditions.”  Physiological homeostasis, or physical equilibrium, is the internal process animals use to maintain their health and life: “the complex chain of internal chemical reactions that keep the pH of its blood steady, its tissues fed, and the immune system functioning” (Muha, 2006).
 
How Stress Affects Fish
 
Stress is caused by placing a fish in a situation which is beyond its normal level of tolerance (Francis-Floyd, 1990).  Stress makes it more difficult for the fish to regulate the normal day-to-day physiological functions—the homeostasis—that are essential to its life.  Dr. Cliff Swanson, associate professor at North Carolina’s College of Veterinary Medicine, says that stress creates “a fundamental physiological shift in fish, from energy storage to energy usage—the fight or flight response” (Muha, 2005).  The survival of any organism depends upon its ability to keep its internal chemical balance from fluctuating too much.  When critical energy is being used to fight stress, it is diverted away from other functions.  The fish must then work much harder just to “keep going.”  Laura Muha (Muha, 2006) likens this to driving a car up a steep hill: it takes more gas (energy) and effort to maintain the same speed as on level ground (level being the norm for the fish).
 
The effects of stress on fish are very complicated physiologically, and are often subtle.  There may or may not be external signs discernible to us—it can continue for weeks and even months, sometimes up to the point when the fish just suddenly dies.  The reasons for this are involved.
 
Adrenaline released during the stress response increases blood flow to the gills to provide for the increased oxygen demands of stress.  The release of adrenaline into the blood stream elevates the heart rate, blood flow and blood pressure.  This increases the volume of blood in vessels contained within the gills, increasing the surface area of the gills to help the fish absorb more oxygen from the water.  The elevated blood flow allows increased oxygen uptake for respiration but also increases the permeability of the gills to water and ions.  This is what is known as the osmorespiratory compromise (Folmar & Dickhoff, 1980; Mazeaud et al., 1977).  In freshwater fish, this increases water influx and ion losses.  This is more critical in small fish than larger due to the gill surface to body mass ratio (Bartelme, 2004).
 
Short-term stress will cause an increase in heart rate, blood pressure, and respiration as described in the preceding paragraph.  The fish can only maintain these altered states for a short and finite period of time before they will either adapt or (more often) the stress will become chronic.  During this initial stage the fish may look and act relatively normal, but it is depleting energy reserves because of the extra physiological requirements placed upon it.  At the chronic stage the hormone cortisol is released, which is responsible for many of the negative health effects associated with stress.
 
One of the most characteristic aspects of stress in fish is osmoregulatory disturbance, which is related to the effects of both catecholamine and cortisol hormones.  The extent of the disturbance following stress depends upon the ionic and osmotic gradients (difference) between the internal fluids of the fish and its surrounding environment (water)—something we will explore in more detail later.  If the stress is persistent and of sufficient intensity, changes in the cellular structure of the gills may occur under the influence of cortisol.  In this situation, increased death and turnover rates of branchial epithelial cells leads to accelerated aging of the gills.  These degenerating and newly-formed gill cells do not function normally, which further limits the fish's ability to maintain water and ion homeostasis under stressful conditions.  Thus, acute stress limits the fish's capacity to osmoregulate, and prolonged periods of extreme stress may result in osmotic shock and death (Bartelme, 2004).
 
Chronic stress impacts negatively on fish growth, digestion, and reproduction.  It is the main cause of deterioration in the slime coat.  It significantly lowers the ability of the immune system to respond effectively and fully.  And in all cases—stress reduces the fish’s lifespan.
 
Hope this helps in understanding what is occurring in your aquarium.
 
Wow! That is a really informative post. Thank you very much! ^_^
 
What I have gathered here is if the Gourami is even in the same tank as the Tiger barbs, that presence of a semi-aggressive fish can cause the fish stress?
 
Is this the case when the two species are on different levels, as the Gouramis are starting to stay nearer the top of the tank where the barbs are staying slightly lower down - almost as if a territory is marked, or rather, an 'allocated space'. I guess I am over-thinking this a little in terms of fish but is there any possible way to have these in the tank? What about if the supposedly stressed fish is no longer being attacked - would it still exhibit that instinctive fear?
 
What I have gathered here is if the Gourami is even in the same tank as the Tiger barbs, that presence of a semi-aggressive fish can cause the fish stress?
 
 
Yes, generally.  It is impossible to know definitively what any individual fish may be experiencing, so we rely on the normal from the observations and work of ichthyologists.  We know how each species behaves, normally, so we can predict when trouble is more likely to occur.  It is always better to assume the norm and provide accordingly.
 
Is this the case when the two species are on different levels, as the Gouramis are starting to stay nearer the top of the tank where the barbs are staying slightly lower down - almost as if a territory is marked, or rather, an 'allocated space'.
 
 
What you are seeing with respect to the area of the water column being used by each species is normal for the species and not necessarily caused by the interaction issue.  Gourami naturally prefer the upper level of water, as they remain near the surface among floating plants.  Being anabantids, they all breathe air, so this is part of it; they also build bubblenests (a few species do not) and these are at the surface.  They also feed primarily on insects on the surface.  So they have evolved to be basically "surface" dwellers.  By contrast, the barbs are cyprinids that generally speaking prefer the mid-level of the aquarium.  They move around all over of course, but most species tend to remain mainly in the middle.  Most fish species have preferences like this, so this is one of the aspects of a fish species that should be considered when acquiring fish; having all the fish at the bottom will leave a large part of the aquarium lifeless.
 
I guess I am over-thinking this a little in terms of fish but is there any possible way to have these in the tank? What about if the supposedly stressed fish is no longer being attacked - would it still exhibit that instinctive fear?
 
 
This picks up from the first answer above.  Gourami should not be combined with Tiger Barbs simply because of the risk.  The two fish are at opposite ends of several things; gourami are sedate, quiet fish, barbs are active swimmers, and this combination is almost always trouble.  Then there is the probability that some if not all of the barbs will be tempted to fin nip when presented with such a sedate fish.
 
As I set out in that lengthy post, fish can be under stress just from the presence of the other species even if no physical interaction occurs.  Ichthyologists have carried out studies with imitation fish models and with fish in side-by-side tanks where there obviously was no chemical scents, and the mere sight of the fish caused stress.  Fish are living creatures, and while we don't know everything about their mental capacity for a lot of things, we are learning that they are more perceptive than used to be believed.  And it is simply not in the best interests of any fish to place it in an environment which can be considered likely to cause it stress.  That is why so many of us advocate research before acquisition.  I will not buy any fish unless I know where it comes from, what it needs, how it behaves, its maximum size, etc.  I know this has saved many fish over the years.
 
Byron.
 
I wouldn't go much with details but as you may have learned, tiger barbs are a big no, no with non-barb/non-cyprinid tank mates lol. Good luck and enjoy! :)
 

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