I will now take the time to completely move off topic and talk about visual threat displays in cichlids. Firemouths and their genus (Thorichthys) are one of the few cichlids that have evolved a mechanism to reduce the amount of energy expended when defending their territory. Cichlids as a group are extremely territorial, and males usually go for the full blown method of defence; attack. As a way of defending your livelihood, it is a good technique. It is fast, as the biggest male usually wins, but often wounds are sustained which need healing. This healing, together with the actual act of fighting, incurs a cost to the fish, that of using energy from food to provide energy to perform these two acts. This energy would have been spent normally on getting big, and thus the fish is able to win more fights. Cichlids don’t have great eye sight, and as they usually live at the bottom of rivers and lakes, visuals are not normally that important, so they are usually dull in colour, or coloured in very obvious patterns (the convict is a good example, being banded completely in black and white). Firemouths have however evolved a method of defence which reduces the energy lost by fighting. The red throat from which they get their common name can be expanded to produce a very obvious signal. Indeed, in a study by Evans and Norris (1996), males with larger and redder throats won more display conflicts than those that did not, regardless of size! So, a very large, but dull male would lose to a colourful, but much smaller male. Only if the opponents are matched in colour will they actually fight. Interestingly, and again, in opposition to most cichlids, female Thorichthys are almost as colourful as males, but smaller. In normal cichlid pairs, the male defends the territory, leaving the female to tend the eggs and fry, but with these guys, both sexes help defend. This makes the territory more secure, and ensures better survival for the fry.
But how have they evolved this method of display? With a cichlids standard eye sight and choice of habitat this display would not really be seen! It would seem then that Thorichthys have evolved better eyesight than normal cichlids, but also live in clearer waters where they can see each other properly. But to my knowledge this experiment has never been carried out! Never mind. Interestingly, you may have seen Jon or I blogging about out Thorichthys sp. “Mixteco Blue”, an undiscribed species. These guys don’t have the same throats as Firemouths, but it will be interesting to see if they have the same displays. Anyway, to the crux of this blog.
Jon spoke about white Firemouths the other day (photo above), presumably these are either albinos, or leucistic. Either way, these guys don’t have the red throats that are as we have seen an integral part of their lifestyle. So, will this change their display? I would expect that it does. If we can get hold of some of these guys and raise them to adulthood, we will be able to perform experiments on them to see if the display is actually present or if they omit it completely and resort straight away to violence. If they do try to display, what will the outcome be? As the red is reduced drastically, with they just give up and fight? But my main point is that if these fish do display to each other, fail to resolve the struggle visually and end up fighting, is it right to breed fish which are unable to perform their natural behaviour? Personally, I don’t think it is. We will certainly be having a go at breeding them, but not to sell on the offspring, but just to see if there is any change in behaviour, but I am sure most who keep them will not be so scrupulous. I would love to know if it is just me who thinks this, or if I have any more support out there!