inbreeding

point for discussion.
in the last few years i have noticed chronic signs of inbreeding in available tanganyikans such as altolamprologus, lamprologus, juliedochromis and especially the shelldwellers. the two species most obviously affected are brevis and multifasciatus which look like dumpy mishapen caricatures of their wild cousins.
anyway i am interested to read others views on this subject.

I don't know enough about Tangs,but I noticed this about 2-3yr ago with South and Central American cichlids,the green terror and blue acara being the most noticeably affected.The local shops all stocked horrific looking examples,that should never have passed the culling stage.Angelfish and discus are commonly seen suffering from deformities and other symptons of in-breeding,and also mass breeding to meet demand.
Another is the celestial pearl danio or whatever they're calling it this month,some pretty horrific specimens in shops.
I guess alot of it comes from Asian suppliers,who just pump the fish out as fast as they can,bought up rapidly with all sorts of chemicals added for one reason or another.Some of the Czech stuff isn't as good as it use to be either,I guess it got a good name,and because of that the demand grew,so the breeding and raising standards were lowered.A lot of it comes down to the fact that to these breeders,the more fish they pump out,and the quicker,the more money they make.

Although I'm relatively new to fishkeeping, I have studied genetics to a moderate level, so hope you don't mind me giving my two cents.
The biggest problem I can see is the attitude of fish keepers to the stock they keep. We all want the best looking fish we can possibly get, so demand for perfect, pure specimens is at a premium. This leads to vast breeding houses being set up where control of the breeding stock is solely influenced by what fish is in vogue at the time. This leads to very close inbreeding that is much less common in the wild. Two siblings, or even a parent and sibling are mated to maintain a desired characteristic. In the wild, fish are naturally prevented from doing this through predation and population dispersal, leaving the gene pool to naturally weed out weak genetic mutations. When fish are inbred in captivity, it is easier for these negative genes to be carried through successive generations, that are subsequently also inbred. The resulting phenotypes of these fish may be very attractive and popular to the aquarist, but increase the chances of rogue genes affecting sucessive generations. If these result in negaitve mutations, there are a number of health problms that can occur in the offspring, resulting in the sub-standard specimens Derek mentioned. However, to make money, the breeder may sell on these weaker fish regardless. As Acara mentions, they should have been culled earlier instead of being introduced to the market. However, with demand in some markets (eg. Discus) for ever more exotic new breeds, competition is rife amongst breeders. As a result, inbreeding, or the more acceptable term, line breeding, ensures a very small gene pool that is incapable of weeding out the genetic mutations in a way that nature has been doing for the past few billion years.
It doesn't take too many generations for these genes to become common in an inbred gene pool, so I think there is an onus on our parts as fish-keepers/breeders to ensure that any breeding we do should be of two fish that are removed by a few generations from each other. I don't know how prevalent it is, but I read one member on this forum offer another member a wife-swap between their fish for breeding purposes. I hope this is a regular occurence to ensure that even these captive fish can have a chance of maintaining a genotype, and also phenotype, as close as possible to that of their wild brethren.
I would like to hear other members' opinions regarding these sub-standard fish in relation to line-breeding. I think this is an interesting topic that the member has brought up.
-Lorcan.

I think the inbreeding issue is important to consider but ultimately there is demand for ever more exotic looking colour morphs and unusual phenotypes and the demand is coming from fishkeepers themselves. There is a distinction between line breeding and simple inbreeding though and I think it's important to stress that. A certain amount of inbreeding to fix desirable traits and to remove undesirable traits from a particular lineage can have huge advantages (not only in producing fish that are more sought after by keepers and thus command a better price, but also in improving fecundity, growth rate, vigor etc). But this is very different to simply allowing siblings to pair and reproduce over many generations, which can have drastic implications for the health of the fish, not to mention their appearance. Dwarfism and deformities are perhaps the most obvious signs but it is important to note that deformities alone do not necessarily indicate chronic inbreeding, particularly for egg layers where the developing embryo is at particular risk from soluble contaminants like heavy metals or organic compounds.
I think the only way to encourage more careful breeding commercially is to refrain from purchasing fish from suppliers that carry poor quality captive bred fish.
For those breeding fish at home, it's definitely a good idea to pay close attention to offspring so that the runts can be culled and only the most vigorous selected for further breeding to limit the fixation of negative traits in your line.

Apart from the overt phenotypes seen in in-breeding, concern must also be directed to the covert phenotypes.

More often than not, breeders will select for colour and shape......how many breeders try to select for glycogen metobalism??

Whilst glycogen metabolism etc may not be great selling point for a breeder of new morphs, it is pretty important to the fish (well....maybe it wouldn't be if the fish had gradual brain damage and didn't really care about much in its life). If alleles for vital biochemical processes are not considered in breeding programmes, then that could spell disaster.

But, we even see morphological-come-physiological problems with some colour variations eg certain strains of angel fish with a clearly thin operculum cover.

ian

Tropheus are my main interest in fishkeeping,and i avoid mixing any two variants of moorii together,all though i keep duboisi "maswa" with Ilangi, and duboisi"karilani"with Ikola.Just recently read on a(US)forum that a duboisi had crossed with a moorii,that I'm finding very hard to believe.In almost 3 yrs keeping both moorii and duboisi together,Ive never seen any signs of either spawning together.This is a pic of the net,just to show mixing moorii can always cross at some stage,so best to keep a species only tank or mix with dubs;) .

I'm kinda surprised this topic didn't spark more debate.

Having come back into the hobby after a long absence, I'm stunned by the variety of "man-made" morhps available, but shocked by the state of some of the fish on sale. I'm not really interested in long-finned or golden varieties of species - but that's a personal taste. However, it saddens me to see previously reliable, sturdy bread-and-butter species reduced to feeble delicate shadows of their former selves. I also think its an abomination to breed, sell or own fish which are clearly badly deformed.

I've done a lot of window shopping over the last few months and I havn't bought a single cichlid yet due to the state of some of them. (That's not to say that there aren't plenty of good fish and good shops out there - I'm just being far more cautious).

There's probably nothing much we can do about in-breeding and line-breeding in the far east etc. where stock is being mass produced, except to vote with our feet and not purchase. But closer to home, whilst you can get away with in-breeding for a few generations, what's the point? As Ian pointed out, there may not be visible deformities, but you may be losing genes from your restricted gene-pool and allowing recessive genes to pair-up and build up in your species population.

Derek's question probably goes all the way to the root of "why do we keep fish?"

Jim wrote:

I'm kinda surprised this topic didn't spark more debate.

i'm pretty sure there was a simular thread quite recently

i have to agree with Derek on this one, the quality of a lot of fish coming in is not great, thats why whenever i can i buy wilds or f1's these i cross breed with standard stock and it really can improve tank bred strains. it is an unfortunate side effect of this hobby that this does happen, anyone breeding or thinking of breeding would be well advised to buy their stock from differing sources at different times so you can be someway sure of not getting fish from the same linebred batches, and if at all possible get a couple of wilds into the mix, yes i know they are more expensive and harder to get but it will only do the fish and the hobby good to preserve the purity of fish species

On the other hand tank in bred Discus are stronger than wild stock, tank bred clown fish are also more hardy than will caught, hey dont forget the British and even the Spanish royal family are all in bred to:laugh:

What's to stop crossing via stray Milt at a time when a female of another pair are spawning? after all, it's within the confines of a sealed Aquarium with a relatively low dilution rate.

Kev.

Nothing is stoping this happeing but the more likely result in a tank is the flow will be so strong and concentrated by camparison to nature that it misses eggs completely and is taken up by the filter