Hi guys,
Is it true that livebearers breeding can make bns more likely to breed?
I've got a guppy that gives birth every 2 weeks and I have about 20 baby guppies but
my catfish have never bred before. I think my pepps are too young though. Not sure how old they are but the biggest is 7cm.

there is a lot of debate of this. while there are some people who suggest it is true there is no hard evidence to suggest that it is true.

http://www.bristlenoseworld.com/t1768-breeding-bristlenose-what-effect-to-hormones-have?highlight=hormones

Thing is with bn catfish. The common/variants and Peps don't really need the help of hormones from other fish to get them going. When they are ready to breed they will Do so (mostly when your least expecting it :| ) Contrary to what people think peps are no harder to breed they just take a bit longer to mature. With them your looking at around 20-24 months to reach maturity

Aww that's gonna take ages T_T I'm such an impatient person too. Oh well the guppies are a lot more active than the pepps anyway, everyone thought my tank was empty when I only had peppermints in it.
It'd be a good experiment to see if that fish hormone stuff works.

Thanks

I'd say 50-50
In one of my tanks, the L144 couple - tankmates are Guppies - is a regular clockwork.
In the other, common BNs - Mollies are the tankmates - nothing happens.

So, I dunno. :roll:

the problem with this is to be sure then you need to remove all confounding factors. which is not easy. sorry, its the scientist coming out in me. I would love to study it one day but i need some funding first

Well, Doug you are the one who prevents this site to drift into a pile of BS (bullshit).

So, could you please give guidance in more details? Or where could I read about this?

There is an article HERE about male swordtails using pheromones in thier urine to attract females, but whether this can effect other fish is not mentioned.

alright, give some time to re read the literature on the issue and i'll summerise it tomorrow

The problem is correlation does not always mean causation, especially when biological units are involved. A lot of people see correlations when things happen in their tanks, and chalk it up to some sort of occurrence, but it might not be the truth, and tbh that's what it seems like here, imo. Afaik livebearers breeding have nothing to do with causing BNs to breed at all. Yes certain hormones are released, but that's like saying a rhino's hormone makes us want to breed. Guppies and BNs are as different as chimps and kangaroos, chances are it just won't work like that. =))

Ok, so here we go...

The idea that there are chemical or hormaonal cues to breeding is not new or indeed flase. There is a small body of evidence that suggests that some species of fish do in fact use hormonal cues to trigger breeding behaviour. One study in particular looked at hormonal cues in goldfish and found that a specific chemical cue released during breeding would indeed trigger other goldfish to breed. There is a lot of fuzzy information about the same thing with guppies. When i say fuzzy i mean that it is from people like us on the web who have seen a link between one thing and another and have therefore decided it to be true and the myth has persisted. The issue with this is that when it come to breeding cues there are far too many to really control in the confines of our living rooms, or indeed out fish rooms. Sure we can control temperature, water quality, water changes etc but there are also effects that we can not control such as atmospheric pressure. When it comes to the link between a guppy spawning and a bristlenose spawning there is no credible evidence that suggests this to be the case.

However, it is not beyond the relms of reason that there is some sort of cheimical cue. It is well established for example that Discus secrete a hormone into the water that inhibits growth to stop them outgrowing a body of water. The issue for me is that this hormone has no effect on angels, who are very closely related. In fact it seems that angels do not have this ability at all. So, if this hormone will not cross the species border to a cousin species then it seem unlikely that a breeding hormone would cross the rather large phylogenetic gap between say guppies and bristlenose.

In order to test this with any real scientific method the process is actually quite simple, however, it does require some serious equipment. Basically the process goes that you examine the chemical content in the water in the lead up and through the spawning process looking for any spikes in hormones. If a spike is detected then that compound needs to be identified and harvested. Then it can be introduced into a 'clean tank' to see if it triggers breeding behaviour. This process would need to be replicated several times to ensure that the observed outcome is not simply a result of chance.

This is obviously a very simple look at it. I would not really recommend people going into the reading behind it for several reasons, firstly it is quite boring, very technical scientific writing and second most of it is password protected and you need to have access to various databases in order to get it. if people want me to go into more detail then please ask.