This is the forth blog i've written since I created my website. So far, I've talked quite a bit about various Rainbows I've been breeding or have raised. Now, I'm going to do something a bit different, and talk about my observations of Rainbowfish behaviour. Rainbowfish have captivated my attention more than any other fish species because when they're 'on,' they have to be amongst some of the most beautiful fish on the planet. Lets face it though, they're not always 'on,' and although sometimes this can be frustrating for us, in that we want our fish to 'perform' or show their best when we want them too, the fact that they only show their best colours at certain times is perhaps what makes them so special. This got me thinking! At first I was wondering how I can tell if my Rainbowfish are 'happy.' In saying that, I'm not sure I believe that fish can be 'happy,' certainly not in the human sense of the word, so perhaps a more appropriate question seems to be 'how can I tell if my rainbowfish are healthy?' Health in its most basic human terms is about making sure we are feeling good, and a person that feels healthy will act healthy. In the same vein of thought, a fish that feels healthy will act healthy. The behaviour of an ill fish is perhaps one of the first indicators that something is wrong for example listlessness, erratic swimming, not eating, the list goes on. That being said, one thought led to another and so it's also got me thinking about the all the various different forms of behaviour I observe in my rainbowfish, and if I can, I would love to try to properly identify these and understand what they mean. What I want to do first of all is describe the behaviour, and then outline the factors that I feel contribute to it. It is not my intention to turn this article into a scientific write-up, it's a really some musings about the various behaviours I observe so that I can better understand and help other people understand why my fish behave the way they do.
The more I think about this article, the more I realise I have to write. In order to do it justice I'm going to have to split it into two articles, part one this month, and part two the next - Hope you enjoy!
Setting the Scene
Before I can really get in to the ins and out of various forms of behaviour, I believe that the hobbyist that wants to see healthy, natural behaviour in their fish must set the scene by taking into consideration two main areas. I believe that without taking these areas into account they will not get to the opportunity to observe true rainbowfish behavour. These are (1) The Environment in which we keep our fish and (2) The Social Setup Requirements.
1) The Environment...
For most fish keepers, this is basic common sense. Rainbowfish are hardy tropical fish, but you still need to ensure you obey a few key rules. Make sure you keep them at the right temperature (23-26 C is good), at the right pH (something close to neutral) in a tank of the right size for the fish you are keeping and do your water changes (30-50 percent per week). For those who want to go a few steps further, there are three further factors that can really help your rainbowfish show off their colours. Firstly, a dark substrate will help make your fish feel more comfortable. A bright substrate will reflect light back up at the fish causing them to look more pale and less colourful. Secondly, plant your tank. Rainbowfish appreciate a planted tank, and they will respond in kind with an array of natural behaviours, such as breeding and sparring where they show their magnificent colours. Rainbowfish are not 'on' all the time, and so getting them to open up and display natural behaviour should be the goal of anyone that keeps them. They typically breed in the mornings, and it's at this time when the fish exhibit their best colours. My final tip is to strategically place your tank to catch some of the suns rays. This may mean you have to work a bit harder to control algae, but I guarantee you, the sun shows rainbowfish off better than any artificial light can. There's no better way to wake up on the weekend than having a cup of tea while watching the early morning rituals of your rainbowfish!
2) The Social Requirements - Group Mentality
Setting the environment is not the only thing you need to consider if you want your rainbowfish to show their colours. Anyone who has ever taken the time to educate themselves about rainbowfish in terms of their basic needs and requirements will notice one thing almost instantly, they need to be kept in groups! In the wild, rainbowfish live in shoals, some consisting of hundreds of fish. This is first and foremost a defense mechanism against predators, the idea being that the bigger the shoal, the less chance that an individual fish has of being eaten. It's important to emphasise that these fish are not loners, they are not comfortable on their own and they need fish of a similar size to shoal with. In fact, as Brown and Warburton (1999) point out, fish in shoals help to stimulate one another, with increasing shoal sizes serving to increase knowledge transfer and social learning. Whilst having a shoal of a hundred fish is typically not possible in the home aquarium, most articles I have read will typically advise that they should be kept in groups of at least six, with equal ratios of males to females. Thus the basic logic is, if you want your rainbowfish to 'feel comfortable,' you need to keep it in a group. A lone fish will exhabit signs of stress, washed out colouration and this will inevitably lead to stress induced health issues. On the other hand, keeping your rainbowfish in groups of 6+ is a major step in the right direction towards ensuring that your fish are healthy and exhibit their best colours.
The Behaviours
1. Sparring - the establishment of breeding hierarchy!
When I think about sparring, I usually conjure an image of Dartanian from the 3 musketeers fighting a duel, lots of flamboyance, lots of colour and lots of attitude. Minus the sword, this is pretty much what you get when it comes to watching rainbowfish spar, and they seem to do this from a very early age. I have three male Melanotaenia Picta of a similar size, and every few weeks they start to challenge each other for the breeding rights in the tank. Their dorsal fins and anal fins arch, their colours fire up in various hues of blues and greens, offset with the red trim of the fins and tail. You truly see every colour of the rainbow! They circle each other, occasionally bumping each other, racing and chasing each other through the tank. The sparring itself is all about the flamboyant show in order to establish a breeding hierarchy, with the winner getting the best spot in the tank to entice in the females. There is rarely any damage done to either duelist, nevertheless, this is still aggression, and the secret to keeping the aggression healthy, and preventing it from turning into something that will stress out and eventually kill the loser is having more than two males. Having more than two will help spread out this aggression and will substantially reduce the risk of mortality. The video below shows my Melanotaenia Picta sparring when they were only 6 months old.
Sparring occurs within and between species. This is likely due to the fact that in the home aquarium, males of various species are able to produce offspring with females of various species (hybridisation - i'll say more about this in another article). As a result, males from various rainbowfish species must establish the hierarchy within a shoal that could include multiple different species. From my observations, rainbowfish only tend to spar with fish that are their own size. I have never witnessed my 10 cm Melanotaenia Picta sparring with my 5cm Melanotaenia Bosemani, though I often see the Bosemani and similar sized Melanotaenia Parva sparring frequently. It seems that the fish only spar with those whom they deem to be a real threat to their position in the tank hierarchy.
This is probably one of the behaviours that gets me the most excited about rainbowfish. Getting to breed and raise fish is perhaps one of the most fulfilling parts of the hobby and when you think about it, this has to be a strong indication of healthy fish because of the high levels of energy involved. There's lots of activity and 'head twitching' as the males select a spawning spot and then dart about the tank trying to entice, and in some instances corral the female to their chosen spot. Just like they do when they spar, the colours of the male fish fire up, showing off their various hues of colour. For breeding to be successful, the male and female come together and vibrate against each other. When this happens, the female drops eggs and the male fertilises them. They then scoot off very quickly. This specific behaviour is designed to 'swoosh' the eggs away into nearby vegetation, where the young will hopefully be hidden enough from predators that they are able to hatch and will learn to fend for themselves. However, given that the home aquarium is filled with many other hungry mouths, the dropping of eggs usually leads to a sudden flurry of behaviour as other rainbowfish try to get an easy snack. It would be very uncommon for eggs to survive in a community tank, and any that do hatch would be quickly eaten by the tank's inhabitants.
During this courtship, you will notice the 'blaze' on male rainbowfish that extends from the forehead to the dorsal fins. On my male Melanotaenia Bosemani, this 'blaze' looks almost white hot, whilst on my male Chilatherina Bleheri its a bright yellow colour. The blaze can last anything from half a second to perhaps 30 seconds and can be seen even when the fish is in the darkest parts of the tank. The rainbowfish's head also twitches, and it seems to me that this is a further signal to any nearby female that this male rainbowfish is ready for mating. It may also be that the twiching helps to bring female attention to him in the same way that a bright, moving object catches your attention much quicker than a bright object will. Regardless, the results are stunning colours!
3. Front Facing Waggle - "Feed Me"
Most of you will know what i'm talking about when you read the title. I'm pretty sure this is a learned behaviour where the rainbowfish get excited about getting fed. The fish all face the font of the tank, and swim, almost excitedly with a side to side motion. They learn this, because we humans are creatures of habit, I know I am anyway. I feed my fish before I go to work, and I feed them when I come home from work, and probably one more time before I go to bed. Whilst fish are not the brightest animals in the world, they nevertheless learn to associate not only the time but my approach to the tank as a cue that they are going to get fed. Rainbowfish are known for being greedy feeders, and its likely that they may not even be hungry when they do this 'waggle' and so I can either proceed to feed them, after which they go back to whatever it was they were doing, or I can ignore them, and after a short while they likewise will go back to doing whatever it was they were doing. Perhaps it is a step to far to say the fish are communicating with us, but still, the fact that we are able to recognise a behaviour that is linked to human interaction in the micro habitat of the home aquarium has a bit of charm to it.
Anyways folks, that's all for now. Part two to come next month when I've had time to do some more research.
Bibliography
Brown, C., and Warburton, K. (1999) Social Mechanisms Enhance Escape Responses in Shoals of Rainbowfish, Melanotaenia Duboulayi. Environmental Biology of Fishes Vol 56 pp 455-459.