New Brackish Tank

[Imber]

I have a 38-40g tank(not sure exactly) that is on the tail end of the cycle(I hope) and I'm trying to decide how to stock it.

I'm thinking about getting 2 f8s and 2 knight gobies to start. I'd like bumblebees too, but I can't find anywhere locally to buy them. The lfs does have 2 other kinds of gobies labeled purple spot and butterfly(waspfish). Has anyone had any experience keeping these with puffers? Would it be better to get 3 f8s or 3 knight gobies?

Right now the SG is around 1.011 because the lfs keeps their f8s at 1.012 but I might want to lower that when I get them and eventually have it around 1.006. Would this be advisable? If so, how gradually should I do this and do I have to worry about my beneficial bacteria dying off? Will the gobies be happy with the lower sg?

Sorry about all the questions, but I just found this forum and I want to make sure I'm doing everything right.

Thank you!

 

[penguinpimp1990]

the knight likes the sg a little high around 1.010, and the puffer and bumble bee's like the sg a little lower around 1.004. I wouldnt advise keeping all these fish together as the puffer and kinght will occasionally make a snack of them, BUT i do keep these fish together and very rarely does a bee und up missing, just make sure they are fed well and the bees probally wont end as lunch. Make sure to provide alot of hiding spaces to reduce aggression among the fish. All of these fish are territorial espically the knight goby so maybe only 1 kinght goby, but See how the tank works out. Also check the species Index, they have all the fish listed above plus many more brackish fish. Good luck

 

[CFC]

Knight gobies (Stigmatogobius sadanundio) are not high end brackish fish and wont appreciate a SG of 1.010, i certainly wouldn't recomend anything over 1.008 for them and prefferably around the 1.005 range. A couple of m/f pairs of knight gobies in 40 gallons will be fine provided there is a few caves for each pair to choose from, males can be identified by their taller 1st dorsal fin. Knight gobies usually work out fine with figure 8 puffers but be watchfull for the puffers nipping the gobies fins. F8's are also lower end brackish fish (apperently wild populations are freshwater but in captivity seem to do better with a little salt) so lowering the salinity will be good for them too. To bring the salinity down just remove a small ammount of water each day and replace it with freshwater untilyou reach the desired SG
Bumblebee gobies as said will be hunted down and eaten by the knight gobies so are not a good tankmate, i learnt this from experience after adding a breeding pair of knights which wiped out my bumble bee population within a couple of days.
Purple spotted gobies are most likely one of the Morgurnda species, these are freshwater fish that wont last long in brackish conditions.
The waspfish (scientific name Vespicula depressifrons) are not gobies at all but actually members of the scorpion fish family. Like all members of this group they have venemous spines in their fins which can cause painfull wounds which will require hospital treatment so these should only be kept by experienced fish keepers, but if you feel confident with them then they will mix very well with the knights and F8s.

 

[Flumpus]

I have three knight gobies in my 29g brackish tank, along with one figure 8. They all seem to be getting along fine. The gobies have a tendency to chase each other around a bit, but not too violently. The most violent part of the tank is definitely feeding time, but no one gets hurt. The gobies leave the puffer alone for the most part, and are usually in opposite sides of the tank. The gobies each have their own cave/hiding place, and I've gone a couple days without seeing one of 'em. I also seem to have a GIANT ghost shrimp roaming my tank. He's thriving in the brackish water (I think it was CFC that said some are caught in brackish waters). I put seven in, they were meant to be feeders, and all but this one were eaten pretty quickly. This one is a good 3" long and has some red coloring on his face. I can't really tell what it is, because he's hidden most of the time. I actually saw him steal a big chunk of bloodworms while everyone else wasn't looking the other day when feeding them. I think at this point he may actually be too big for anyone in the tank to eat... right now. My puffer is small, and will get quite a bit bigger, so watch out shrimp!

Anyway, my SG is 1.005, and everyone is thriving and active and they all have great colors (especially the gobies, beautiful fish).

 

[penguinpimp1990]

the knight likes the sg a little high around 1.010,

ooops, i was thinking monos, i dont know how i got monos mixed with knights. but anyways the kinght gobies sg should be about 1.005, i keep mine at 1.006 and theyre fine

Bumblebee gobies as said will be hunted down and eaten by the knight gobies so are not a good tankmate, i learnt this from experience after adding a breeding pair of knights which wiped out my bumble bee population within a couple of days.

really? My knight goby rarely eats a bbg, but I only have 1 female knight goby (who is very capable of eting a bbg with her size) in with the bbg's so maybe the breeding part has something to do with it, live foods can help trigger spawning with knight gobies (id assume with a lot of other fish too)

 

[chris_1127]

i've found that my bumblebee goby population has been dwindling slowly - started off with 3 doriaes and 3 xanthazonas but think all bar one of the smaller xanthazonas have been eaten. Ive never seen my figure 8's take an interest in them so assume it must be my knight gobies doing it. Otherwise figure 8's and knights seem to be a great combination

 

[Imber]

Ok thanks all for the advice! I will definitely be bringing the sg down after I get them home unless my lfs has brought his down some. Funny that I'll actually be lowering the sg instead of raising it!

I'll probably just go with a couple knights and a puffer or two unless someone around here starts carrying bbgs and then I might skip the knights and go with them. The waspfish are neat, but they seem to hide a lot and that's kind of scary not knowing where they are while I'm doing my cleaning.

I wish I could give a better description of the "purple spotted goby" but this was a few weeks ago when I saw it and I didn't realize it would be so hard to identify. All I remember is they had it in with the knights and it was mostly a neutral color like brown or grey, but it had some purplish pinkish bluish iridescent spots up by its head and it had the froglike eyes that were raised and closer together. Also, it moved along the bottom and up the side. I never actually saw it swim up into open water. I've looked at lots of different pictures and haven't found it yet so I think you're right about it not being a goby. I hate going to the lfs without buying something so if I think of something I need or if this stupid tank ever cycles I'll try to get a better description.

I've arranged a couple different types of rock and fake plants so that there are some nice hiding places. Also, I put in some small glass and terra cotta type pots. Oh I'm soaking a piece of driftwood too. My ph and kh are both naturally very high and I have crushed coral substrate so I think it should be okay to add?

Right now I'm getting no ammonia readings, high nitrites and decently high nitrates(20 before last week's water change). The nitrates indicate that it's close to being done right? All I've really been doing is 40% changes once a week. Should I do something else to help it like a bigger water change? Sorry about all the questions! All I've had up until now are freshwater tanks which I made all sorts of mistakes with before educating myself so I want to be absolutely sure that I do this one right!

 

[nmonks]

Hello,

The goby sounds like a Morgunda spp., of which the most common are the 'purple spotted gudgeons' Mogurnda adspersa and Mogurnda morgunda. To the best of my knowledge, they are all freshwater fish and should not be kept in brackish water. They may well tolerate very low salinities (~ SG 1.003 or lower) but it isn't good for them. Some species are pretty mean tempered, too. If you want a similar but more peaceful fish, look for the African sleeper goby Dormitator lebretonis. It will do well at low to mid salinities.

Bogwood will still tint the water, even if it has no great effect on pH and hardness. This isn't actually a problem, I think brackish water tanks look more realistic when the water is a bit tea-coloured. But be aware of this before you put the wood in. Coral sand / crushed coral eventually gets coated with bacteria and dirt and stops buffering the water. This is one reason pH and hardness decline in marine tanks even when coral sand substrates are used. I'd rely more on some calcium plus or similar hardening agent added to the filter and replaced every few months. Alternatively, take out some of the substrate periodically and give it a good wash under the hot tap with a little soap. Rinse really well so all the soap has gone, and then let it dry in the sun. Return to the tank, and it'll be as good as new.

If ammonia is zero but nitrites are high, it means you're halfway through the maturation process. If there aren't any fish in the tank yet, there's no real need to do water changes, in my opinion. All you're doing is removing "food" from the bacteria.

Cheers,

Neale