Need Tank Size Suggestions, Please.

[Dave Legacy]

Happy Holidays Everyone,

I've run into a slight aggression situation with my archers and I feel that it may be about that time to consider upgrading their tank to something much larger. The question is; how big? Not so much how big, but what dimensions? Let me first give everyone the run down.

This is my current tank:

I'm currently housing 4 (toxotes microlepis or jaculatrix not 100% sure yet!) in a 40G Breeder(36x15x16) w/about 20-30G of water. I knew when I set this up that at some point I would need to expand because these fish would out grow this tank. I had decided that when they showed signs of growth that I would start up a new tank to be their permanent home. Well they don't seem to have grown at all over the last 3 months, however they are starting to get territorial and one of the archers is getting aggressive towards the other 3. I had thought that being shoaling fish they would all get along... wrong!

This is kind of what I want to setup for them:

My tank will only be about 1/2 filled. I will be using live red mangroves(probably not that many) or another plant that will hang over the water and provide climbing room for crickets. I will be creating more above water "beach" area to house a few mudskippers and fiddler crabs. For fish I will probably keep only the 4 archers that I have and maybe a school of another smaller fish like glassfish or a species of rainbowfish. Really I don't want to get that crowded.

As for equipment I plan to build a sump and drill a hole in the back of the tank to plumb it. Possibly some powerheads to add a slight current depending on what type of biotope I try to recreate.

So that being said, what dimensions will make the best tank for this setup? These are the tanks I've been leaning towards:

175G Sq. = 36x36x31
190G Wide = 48x36x25
240G Sq. = 48x48x25

The idea with square tanks is to give a lot of open swimming area and still have a few islands for the semi-terrestrial critters. Not only that but the channels between and around the islands might divide up territories. I don't know if maybe the longer tank would be better, or maybe something that was even much longer than 48".

Thanks in advance,
David

 

[Dave Legacy]

The dominant archerfish has taken control of the large open area in the middle/right-side of the tank which is causing my other 3 to hide under or on the other side of the stump. If I added a few more tall hairgrasses in the middle might that cause this bully to confine it's territory? She seems to mostly attack when the other fish come into her area, but if they sneak in unnoticed she tends to ignore them all together.

 

[nmonks]

Well, to be honest I suspect you're going to end up with a single dominant fish. That's my experience with archers. But they do work out for some people when kept in groups.

Rearranging some of the decor might help, as would defining specific "lurking" areas. Archers seem to favour certain spots, and if each fish has a shady nook they can occupy, that might help.

Adding more fish may help, too. Need not be actual fish; try using a mirror to fool the meanest fish into spending its time threatening its own reflection. I've seen this work with cichlids. But if you could keep six or seven specimens, that would likely work better than three or four. Same as with tiger barbs, angelfish, etc.

What about some active tankmates, such as scats? These fish can diffuse tension by 'getting in the way' of fights and distracting the line-of-sight. You'd need a fair number, say three or four.

Read up on handling aggression with mbuna; I daresay the same tricks would work here.

I do think a tank 1m or less is too small for a group of archers. It's perhaps fine for a single specimen that isn't too big, but really you're going to want to work with something in the 120 to 150 cm range.

Archers grow slowly. I think mine doubled in size in about two or three years. If they're microlepis, they're not going to get all that big anyway (~12 cm or so in captivity). Provided the dominant fish isn't actually preventing the other fish from feeding, or damaging them, you don't need to worry too much.

Merry Christmas,

Neale

 

[Dave Legacy]

Neale,

Right now my archers are 2" in size. If you don't think it's a problem I could add 2-3 more and see what happens. I'll try out some mirrors for a while and see what they think about more fish being in the tank. I might have the chance to move up to a 60G aquarium in a couple weeks. I might do that for a short time while planning out their permanent home.

As for faster tankmates I'm very interested in Monodactylus argenteus. My only concern with that is that they get quite large and will require a salinty much higher than these archers will in the case that they turn out to be T. Microlepis. I also have considered a school of Bosemani Rainbowfish or Indian Glassfish. I don't know if they'd be fast enough but I know they do like to move around all the time. It seems that these might be better fish to keep if I need to keep a lower SG.

The aggressive fish isn't doing any damge and they're all eating just fine. I just wish should leave everybody alone. I noticed that this morning they were all swimming together and playing follow the leader. The lights were off and the lunar phase was at about 1/2 moon. I don't know why they only get along at certain times. I'll do some research on Mbuna.

Thanks for the advice,
David

 

[nmonks]

Hi David,

Adding some more fish sounds like a good idea.

I'm not a fan of adding rainbow fish to brackish water aquaria; while some species do okay, none are really brackish water fish, and many species prefer neutral water conditions. If you were going to try this, I'd look at some of the larger, hardier Melanotaenia such as fluviatilis and maccullochi. These are fast moving (and fast growing). I think boesmani is, to be frank, a bit too expensive and slow growing to risk with archers, but that's your call.

I agree that monos aren't the ideal fish for this set-up, but that having been said, I've seen many people succeed with these at even relatively low salinities. Indeed, the only recent report of anyone spawning these fish (that I'm aware of) has been in a tank where they were kept in purely freshwater (see January's PFK). Of the three species available to aquarists, the West African mono is the one most likely to do well at low to mid salinities.

Glassfish could work, but the large species are exclusively freshwater fish, and among the smaller species even P. ranga might be small enough to be viewed as prey. Perhaps a better choice for dither fish would be "green" orange chromides, i.e., the wild-type fish. They're really nice fish, peaceful, and do well at mid to low salinities. They're about the right size to be safe with archers, and stay close to the bottom anyway. It's difficult to find the wild-type, though.

Cheers,

Neale

 

[Dave Legacy]

Today I went out to find 2-3 more archers to add to my shoal. Unfortunetly I was only able to find T.chatareus and that wont do. I have believed that my archers are actually T. Microlepis and not T. Jaculatrix. Because of this I have lowered my SG where it is currently at 1.004SG. Since it has dropped to this Specific Gravity the fish have become gloomy and easily stressed. If they were in fact T. Microlepis I would believe that they would rather enjoy the lower salinity water.

Looks like I'll have to experiment somemore and just find some fish that look identical to mine. Mixing species can't be a good idea, am I right?

 

[nmonks]

Hi Dave,

If it was me, I'd take the SG up to 1.008 and leave it there for a while. Even if it's a bit on the high side for T. microlepis it shouldn't do any harm since they're said to enter sea water periodically.

T. jaculatrix don't seem too bothered by suboptimal salinities, and I've usually kept them at SG 1.010 rather than anything higher. They definitely are not as bothered by low salinities are scats or monos.

As for whether mixing species will help with the aggression, I have no idea. On the one hand, they're similar enough that basic communication of stuff like threats and hierarchy should work. But if there's some subtlety involved, the two species might just ignore each other.

Cheers,

Neale