Kostas G said:
Are rainbows better able to protect themselves than Guianacara?
I really couldn't say (?).
CA are often very competitive with other CA. A rainbow is timid and backs down easily, and IME gets no free ride. It's seen as one of them even though it poses no real threat. IME it got bullied excessively, especially by firemouths, and eventually by all the CA in the tank. I don't think being at it's larger size will make any difference. Generally cichlids tend to focus more on other cichlids of the same or similar weight class.
When it comes to dominance of a tank, there can be friction between any cichlid that is in contention for 'top dog'. Of course I dont' see any likely issue here, with a rainbow or Guinacara .
Kostas G said:
Would they still breed without being able to hold the space? What do you mean that it won't come for free?
No, a substrate spawner needs to be able to own at least some space, to the exclusion of all other tankmates, in order to successfully breed. Generally won't lay eggs with out owning the space first, and if they can't defend, the eggs will usually get eaten quickly.
Initially the space is unlikely to be claimed with out at least some battle, however minor or violent. It's got to be "backed up". Can't be running away from the boss of the tank, otherwise the necessary territory isn't being maintained. There is no respect for the boundaries of a territory with out at least some threat of being hit or struck. Some degree of trespassing is often tolerated, but if one of the pair goes towards the trespassing fish, it's got to be on it's way.
Kostas G said:
Both the Platydoras abd plecos are pretty good at sneaking in and eating everything, which I don't mind much but the cichlids mind. My experience with the smaller Microgeophagus and Apistogramma has not been very good. The catfish get bitten fins and the breeding cichlids often die out of the blue(stress?). Would you think it's wise to do it or asking for trouble?
All these cichlids are very hardy compared to some of the smaller dwarf SA. Doubt the bottom feeders would ever stress them too much.....though some of there cichlid tank mates might (?).
Wise or asking for trouble? 1001 possibilities. I think it's less then 50/50 whether the rainbows would even be able to do the deed in the presence of this company; and even then much more likely when all are at a young and small size. The Thorichthys, IMO, a much better chance of breeding. Very possible, especially in the size of your tank, they wouldn 't claim too much space and the aggression would be primarily some threatening along the borders of the territory. But with any substrate spawner, it's very hit or miss with a variety of factors/variables.
Kostas G said:
Did they breed on aquatic plants or closer to the bottom?
Close to the bottom. Most often on the corner of the tank on glass; a few times on flat rock in the middle of the tank.
Few substrate spawners lay eggs closer to the surface. Had convicts last year, lay eggs at the very top corner of the tank
a few times....but it's rather uncommon and unusual.
I lay a flat rock into the back corners of the tank. It's always the preferred spawning site of CA and at least puts the breeding territory to one side of the tank, rather then in the middle.