1) At 5 inches per fish, you'll be looking at a 50% WC every 5 days. At 7 inches, you're looking at a daily 50% WC. This assumes they are fed properly as at small sizes they need ample nutrition.
I'm curious how you got to these numbers. Is there some kind of calculation you used? You really think they would need water changes that often even with the massive amounts of nutrients being taken out through the aquaponics?
Yes, I'm taking the fish length, calculating the girth using similar fish shapes and then calculating a weight for the fish. I am then using the appropriate amount of food needed (given the fish weight and age) and calculating the amount of nitrates being added to the system on a daily basis and using the nitrate level to determine when a 50% water change is needed.
No, I don't know what plants you are using or how many, so I can't make any allowances for it's effect. However, let's say you had an effective plant like pothos and let's say it had around 10 leaves and was growing (not a cutting with one branch and 3 leaves), you would need approximately 18 plants in your system to accommodate a fish load of 4 lbs (around 7 inches length for 30 fish.)
2) A lot of the fish are much more aggressive at feeding while others have narrow food requirements, so some fish will not get adequate food unless very individualized feeding is done
I am aware of the feeding needs of each of these species. That is why I currently have the ENs alone, getting them feeding well before adding anything else. That is also why the only bottom feeders (ENs, eel, ropefish) are all slower, more deliberate, nocturnal feeders. If I have them eating well before they have to compete, and feed them when the lights are off in addition to the daytime feeding, they should be able to get enough. Or that was my thinking at least.
Well, that's a good thing, but the eel will need special attention, and perhaps the knifefish and rope fish as well. The question I raised is whether or not they will all get fed, especially as they get larger.
3) Stress levels will likely be high, so immune systems will be weakened
Could you explain why? All these fish are very peaceful by MF standards.
Many fish are peaceful when they have little competition and plenty of room. In nature, these fish do not live this close together and some of these have never encountered each other in nature. Many have identical needs for food and shelter, which in nature isn't a problem since they can swim away and look for more. In a tank that isn't possible. And, in nature the Peter's EN is aggressive against conspecifics, at least per Fishbase and other sites.
And I'm assuming that you are using sand as for many of these fish, that is important. Bare tanks or gravel could also induce stress to fish that evolved using sand.
4) Eels will grow quite fast if fed properly and will need their own "space"
What do you mean by this? Like his own tank, or a hidey hole?
Fire eels are often kept where they can bury themselves in a substrate or crawl into something like a properly sized pvc pipe. They grow fast when housed and fed properly, with 1" or more per month reasonable. Some post of them reaching 2 feet within a year and a half. To do that they need properly sized food that other fish will not take from them, but many of the fish in the tank are more aggressive feeders (cichlids and tetra). Their food needs might match the EN and the ropefish for example. Which ones would actually eat?
5) Uarus are typically kept in groups, not pairs
I probably would get a few more to begin with and them sell them as they get older when a pair forms. I heard they do fine in pairs when older...
Ok, that's more fish...and what is "older". My post was based upon 5" which is far smaller than Uarus get.
6) If a fish dies in the tank how will you know?
What do you mean?
Are you going to count all 30 fish every day is what I mean. A single dead fish left behind a rock might be all it takes to pollute an over-crowded tank filled with stressed fish. It's easy to notice a missing fish when you have 10, hard when you not only have 30, but many multiples of the same species.
-->None of these fish are very violent are they? That is my understanding at least. The only fish on the list that are somewhat territorial are the cichlids, AKF (?) and the ENs (but they are really mainly territorial with each other, kind of the way loaches are).
There are cichlids which in nature peacefully school together...which will kill each other in a 200 gallon tank. Being unable to swim away and placed where resources are limited is a good recipe for violence. Cichlids are territorial, Fire eels are, Peter's EN is. The tetras and rope fish do not appear to be. Let's assume you have enough territories at 2" in size. That will shrink at 5" and more so at 7". If you had 30 tetras or 30 tinfoil barbs it might not be an issue.
My overall opinion is that you have too many. I'd suggest having 1 set of cichlids (not 2), as the second set can be easily added when you have the larger tank. Uarus and Geos could each be added as group (after a grow out) to a larger tank without disrupting the tank. I'd suggest leaving out the eel or dropping most of the EN as not only does it seem they will compete too closely, but the EN will have a lot of stress with each other. More EN or an eel (after grow out) could be added to the larger tank later where the extra room will allow them to coexist more peaceful. The tetras I would leave out for now as well as those can be added to the larger tank at any time.
You have a nice set of fish no doubt (although I'm not partial to tetras), I like all the other choices. They are interesting, gorgeous and well worth the effort, but some will suffer if you have too many. Too many fish at one time provides the conditions where minor issues, loss of some BB, a dead fish, an ich outbreak, power loss over night, a friend over feeding, etc can become a disaster. I can't imagine how crappy I'd feel if I had raised those fish for 10 months then lost a bunch.
