Ok thanks! I thought that might be the case with the little fish...harlequins are pretty cool although I'd still worry about them with the temperament of my gourami! He's been in both other tanks and hassled everyone but the rummys. I somehow doubt there are any suitable tetras though!
I agree, the gourami might be a risk. These are territorial fish,much like cichlids. And like all fish, individuals within a species can behave differently. This is sometimes due to the environment (meaning, everything in the tank from parameters to decor to fish numbers) and especially tank space. It is known that the smaller the space, the more likely that aggressive tendencies may show up, even in peaceful species. Should this occur here, obviously you would need to move the gourami (or the other fish).
Glad you like the look of the tank, I've always gone for live plants, apart from the benefits for water quality they just look so much better, and they're cheaper than good quality fake ones! I don't know much about them, I've always just picked what I think will look best and come down to a handful of successful species through trial and error - I believe it's amazon swords that I picked for the 54? Not sure what the smaller ones are!
The larger three plants are swords, probably the species
Echinodorus grisebachii var.
bleherae [I'll come back to this], and the small green-leaf plants are
Cryptocoryne species, and the purplish plant is a stem plant, possibly
Ammannia gracilis (I'm not much up on some of these).
The sword plant well known as "
E. bleherae" has long been the most common larger sword in the hobby, but phylogenetic analysis has confirmed what some botanists proposed previously, that this is not a distinct species. What Rataj originally described as the three species
E. bleherae, E. amazonicus, and
E. parviflorus is in fact the same species as
E. grisebachii. Under the international rules of nomenclature the oldest assigned epithet (the second part of a scientific name is called the epithet, the first being the genus) for a species must be valid, so
E. grisebachii is the true name. This name was assigned by the American botanist J.K. Small in 1909, in honour of the German botanist H. Grisebach. Rataj's classification was subsequent to this, so these names are technically synonyms.
This is what we may term a polymorphic species, meaning that it has two or more variants. This occurs in fish too, usually due to geographical separation when a species may begin to alter. When this polymorphic species was originally proposed, phylogenetic analysis of DNA was not applied, and it was more of a hypothesis of sorts. Kasselmann argued that the distinct variation in the physical size and leaf shapes of these "species" was sufficient to retain them as distinct, but DNA shows this is wrong thinking. But it still leaves the question of why a species is so clearly different as it naturally occurs in South America. Samuli Lehtonen (who has done the most exhaustive phylogenetic analysis) has not, to my knowledge, delved into this aspect. Of course, geographic variation within a fish species is very common; a few years ago, ichthyologists determined that the lovely hatchetfish species
Carnegiella marthae has at least three distinct lineages that are separated geographically, and this is certainly not unique to this species. Sometimes this variation can continue until the population may be considered a subspecies, and beyond that a distinct new species.
I'll go for 6-7 sterbas then
It sounds like a lot of fish for the 54, maybe because of the whole molly tank space problem I'd got it into my head that it would be a similar fish-to-volume ratio with the smaller tanks - it seems mad that there will be more fish in the 54 than the 90, but I suppose the corys aren't nearly as active - you seem to be a bit of a fish guru anyway so I'll trust you on that! I hope you know when I question your advice is not that I don't agree with it, I just like to know the rationale behind everything! I may go for either 5 or 7 just because I have an aversion to even numbers (apart from pairs)
I never object to being questioned, and I will always try my best to explain the rationale. We all continue learning, or should at any rate, and I still am for sure.
When it comes to shoaling species, the numbers of fish can affect the biology in more than just overloading it by too many. When a shoaling species is maintained in too few numbers, the fish will tend to be stressed, and this causes physiological issues for the fish, which in turns negatively affects the biological system in the aquarium much more than would be the case with a few more fish. So, all else being equal, it is generally safer to have more of the species rather than too few on the basis of what the biological system can support. In other words, a group of six or seven corys will have less detrimental affect on the system that would three or four.
Considering the tank did have 7 tiger barbs and the gourami and had stable parameters I don't think maintaining should be a problem - just a thought - depending on when I get the corys I may have lost a large part of my nitrifying bacteria! Do you think it's worth trying to maintain the levels I had (sufficient for a fully stocked tank) by shoving the same amount of food in as I would have done feeding all the tigers/gourami? Providing the rams didn't try to eat it all! Or just introduce a few corys at a time?
Bacteria does not die off like we used to think. Once present, if its food should lessen, the nitrifying bacteria (and nitrifying archaea are also involved at this stage) can go into what we can think of as a hibernation, or suspended state. The length of time this can last varies, but most now believe it is a matter of weeks, if not months, subject to other factors. Also, your live plants help here. Plants need nitrogen, and aquatic species (most of them) prefer ammonium, so they will take up ammonia/ammonium fairly rapidly. This is the premise behind "silent cycling" where live plants, including some fast growing species (floating are ideal for this) are started, and then fish can be added slowly with no problem. I've set up dozens of tanks this way. Of course, there will be nitrifyiers on the plant leaves (if they come from tanks with fish) and wood from existing tanks. But the plants themselves do a surprisingly good job of dealing with the ammonia. And of course this process does not produce nitrite, so that second stage is non-existent to any degree.
Therefore, I would add all the corys at once. Another benefit of this is that they will settle in faster the more there are. This is very important with any shoaling species; the fish will certainly become established quicker, and in cases of species with hierarchies this is also much safer than adding fish sporadically.
Byron.