Seems like you already got some great advice. I’ll just add/reiterate…
(1) 20-gallon tank w/ 20 fish is kind of tight (especially when your shark and angelfish grow up). Let attrition get it down to happier levels. It sounds like you are doing well monitoring the water quality, so it may just be a matter of overcrowding (stress, fighting, etc.). 10 mid-sized, or maybe 15 small, tropical fish may work. If you had a saltwater tank, the number would drop to 1-2 (or maybe 3 small) fish…saltwater fish are much more susceptible to stress from overcrowding.
(2) as for RickJay, I too have had good luck keeping a ‘fighting’ betta with other non-bettas. There was no conflict. But I’ve only tried it twice.
(3) Once they get settled, they should survive better. The sudden new environs may be causing the problem. Did you add the fish all at once or a few every few days? Adding them all at once could have been stressful for them. On the other hand, adding new fish to an established tank can make it tough for the newbies because the other fish have already claimed the best hiding places. (One trick is to shuffle the decorations in the tank when adding new fish.)
(4) Has the water quality been stable or does it fluctuate a lot over the course of the day. This is not usually a big concern for the tropical fish you have, but it’s a possibility. Is the tank next to a window or heat vent that may cause fluctuations?
(5) It happens. Do you best. Let the system find its equilibrium and don’t push it.
One other thing, instead of focussing on the greatest number of fish, aim at buying fish that behave in different ways and inhabit different parts of the tank. Some, like your hatchets, will stay at the top. Your corys will hang at the bottom. The others will incorporate all ranges. Your danios will dart around quickly, your gouramis will glide gracefully. Seeing them act as schools is really cool. You are missing out on something if you do not have that as a goal. Of course, that necessarily limits diversity.
No matter how big it might seem to you, 20 gallons is not really a big tank. And I’m not sure why you would want to “rent and return” fish instead of building a healthy environment. Angels are really cool fish. But they do live a long time and get really big. Same with gouramis, plecos, and sharks.
The 30 gallon tank I’ve been working on lately I think is really rounding into shape. It has:
2 Angels (3-4" each)
6 serpae tetras
4 black tetras
3 corys
2 glow light tetras (holdovers)
So my tank has 50% more volume than yours, and one less fish than you initially tossed in yours. Not to say I’m doing everything the way it has to be done with this one tank of mine, but just trying to give you some info.
And in my opinion, it looks pretty good. Certainly does not look empty. Haven’t had any deaths in some time, and recently completed my conversion to all live plants. When the glow lites go, if I add anything, it will be to increase the schools of tetras and cats.
Someone told me once that to your fish, you are God. That made an impression on me. Not to say I get all busted up when one of them cacks. But you do control their lives completely. And I think it behooves you to do so responsibly.
Big Al’s does have great prices on your more popular fish, but at $2.50 and 4 for $9 I think they’re cheap when you look at the next tank and a pleco is $25.
]QUOTE]**Get another betta and put him in a little 5 gallon aquarium all by himself, and get one of those lightweight locker mirrors and tape it to the outside of the tank (on the side, so it doesn’t block the view). He’ll display to himself (and the room in general) for hours and hours, every day. **
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Actually, it occurred to me that a betta bowl would look really nice in my office (I have my own, not a cubicle.) But here’s a question; if I have a simple little 2.5-5 gallon tank for one betta, what level of filtration is required? Would I actually need a pump or an airstone for one lousy fish?
By the way, I should do a fish recount. I now have
My experience with betta bowls has not been good, mainly because you need to do a daily water change to keep it clean enough for him. Also, it tends to get that weird scum on the top, which is part house dust and part bacteria, I think.
For a 5 gallon tank, I wouldn’t worry about any kind of filtration, as long as it was just the betta. Just do a 10% water change every week, by scooping out some old water and putting in some new water. In the wild, bettas live in still water, so he doesn’t really need a bubbler. When you see the bottom has gunk all over it, scoop him out with most of his old water (from the top of the tank), put him in another tank or bowl, and scrub out the tank. Cover his temporary home so he can’t flip himself out.
And watch the pH if you live in an area with really alkaline or acid water. It can creep up (or down) on you. I don’t recall that my bettas were really picky, but once it got to a certain level, they just weren’t happy. Our water here (downstate Illinois) is about pH 9.0 straight out of the tap. All the reputable fish stores in the area have signs warning people about this. You add sodium biphosphate to lower the pH. I’m not sure what you do if it’s too acid to begin with.
Another concern with a betta in a tiny tank is temperature. He wants it warm. If your office is nice and warm, then you won’t need a heater. But if it isn’t, then go with at least a 5 gallon tank and the smallest size heater. It’s difficult to get a really small tank like a 2 gallon to stabilize with a heater. There’s not enough water for fluctuations, and it’s always either too hot or too cold. The thermostat needs time to expand and contract and send the message to the heating element.
Also, watch it carefully for a week or so before you put him in there, because before the thermostat gets calibrated to your room conditions, you can look over there and realize that he’s basically cooking in 85 degree water. Give him his very own thermometer (and don’t waste your money on the heat-sensitive self-adhesive ones–they really suck. Get a regular hang-over-the-side metal/glass-tube- with-alcohol thermometer, they’re more reliable.)
