Adjusting fish population - advice?

[malloc]

Hello,

My gf & I have a 20 gal tank that has been running about 6 months now. We had no idea what we were doing (and still don't reallt =P) but we unfortunately took the word of several different petco employees without doing much research. This is what we have in the tank now...
3 Odessa Barbs
2 Tiger Barbs
3 Marbled Hatchetfish
3 Serpae Tetras
2 Glowlite Tetras
2 Sunburst Plattys
1 Otocinclus
1 Rainbow Shark
1 African Dwarf Frog
1 Apple Snail

Pretty random assortment. Anyways, we were regretting our random choice of fish based on what looked nice in the store rather than planning out what the final population would look like. We seem to have many schooling fish in small groups & they seem unhappy. The glowlites, for example, just sort of sulk in corners by themselves. We were thinking of trying to get rid of the glowlites & the serpaes, and maybe getting 1 or 2 more tiger barbs, just so we have larger groups of species.

We were also wondering if we have too many fish in there. Right now, most of the fish are not much more than 1", which puts us just barely over 1" per gallon, but we are beginniners. we thought it might be a good idea to have a few less fish in there until we get the hang of it.

Any thoughts? is it a good idea to swap these fish out? will the lfs or petco or petsmart take our fish?

 

[coldmachineUK]

Welcome to AA, and don't worry about things: we all make mistakes (#1 being relying on LFS employee advice ).

I think your tank is a little overstocked for a 20G, unfortunately

Here's some info:

1. The tiger barbs are fairly aggressive fish. They go well with your rainbow (red-finned) shark though, and possibly with the serpae tetra, but definitely not with the glowlights.

2. Your oto needs friends if you keep him. They love company!

3. Your glowlights are among the worst type of tetra when it comes to schooling. And, they won't school with serpae for sure. You can get away with grouping cardinals and neons together, for example (and I even manage to get away with a school of white cloud mountain minnows who group up with my neons). So, I would go with one of these but not both.

4. Hatchetfish? You're daring! They're amazing at jumping, you will have to be careful and keep a tight lid on the tank.

Here are the group number recommendations for your fish:
Hatchetfish: 5-6+ for schooling
Serpae: 5-6+ to reduce nipping
Tiger Barb: 5-6+ to reduce nipping
Glowlight: tend not to school like other tetra do unfortunately. But 6+ and it might help.
Oto: 3+
Shark: 1

I would:

a) Decide between odessa barbs and tiger barbs and take one group of them back.
b) Once one group of barbs is gone, I'd increase the numbers of the other to 6.
c) I'd take back the glowlights.
d) I'd take back the hatchetfish. These are skittish fish and living with those barbs is going to eventually stress them out. You also need more of them and the tank is too small for that along with a group of barbs too.
e) Keep the shark with one group of barbs.
f) Read up about the ADF because I don't know anything about them! Hehehe. Ask others on here about that: I really have no clue if they're a suitable tankmate for what I'm suggesting.
g) I think the apple snail is going to get nipped at by the barbs (and possibly the shark). You may want to consider sending him back too
h) Consider taking back the platies too. They're very peaceful and may get nipped at by the barbs.
i) Keep a group of 4 serpae tetra.

So then we have:
a) One group of 6 tiger or odessa barbs
b) One group of 4 serpae tetra
b) One redfinned shark
c) Possibly one ADF
This would make your tank a semi-aggressive tank, which would be fine.

People may have other recommendations though. It may be possible to keep the odessa and the tigers together and increase numbers to 4 for each group (and leave out the serpae), but you would need to keep an eye on aggression. The hatchetfish I really wouldn't leave in there whatever you decide to do.
You will also need to keep up with pwcs

 

[malloc]

Thanks a lot for the info, but my experience so far has not corresponded to what you say. As it is right now, everyone gets along very well. The hatchetfish are the oldest fish in there right now, they have always been *completely* ignored by everyone, including the barbs. They also seem to be schooling very well with just the 3 of them. They can usually be found swimming around in a tight circle up at the top....kind of funny, like a dog chasing his tail. As is it now, the only nipping that goes on is between the serpae tetras- they never go after anyone else. I actually do have 2 otos, that was a typo =) I was worried about the tiger barbs' aggression at first too, but the ones we got are very young & small & seem to be pretty good friends with the odessa barbs. The plattys actually nip the snail more than anyone else, the shark sort of licks his shell occasionally, but other than that he gets left alone most of the time. I think most of the fish avoid the adf because when he was young he had trouble controlling the direction he was swimming in & would often charge headlong right into a fish =P

 

[coldmachineUK]

Ok, just posting advice on stocking tips as requested. There's a saying that "if you have to ask, the answer is probably no"

If things are going ok, no need to change them.

 

[malloc]

If things are going ok, no need to change them.

Thanks, this is mostly what I wanted to hear. I'd hate to have to give up so many fish, I'm pretty attached to most of them =)
I think I'll start out by getting rid of the tetras, and see how things go from there.

Do the barbs ever get more aggressive as they grow? Like I said, they are doing well now, but they are also smaller than the rest of the fish.

Also, will most fish stores take fish back without a fuss? Seems like it could be risky for them if they were to unknowingly accept diseased fish, etc...

EDIT:
Well, I took back all the tetras today. It's hard giving up fish you've been taking care of for so long, even if they werent your favorites. One of the tiger barbs was actually dead when I got home from school as well, so it's been a sad day. Will prob. take back the last tiger barb as you suggest, and possibly the plattys. Think I'm going to give the tank some time to rest before getting any new fish though. There is another post around here where I ask about my water being cloudy, and losing that tiger barb seems to indicate there are bad things going on.

So, I should be left with 3 odessa barbs, 3 hatchetfish, 2 otos, 1 rainbow shark, the snail & the frog. The odessa barbs seem content as they are, so I don't feel a lot of pressure to get more of them, and I'm pretty attached to the hatchetfish I would kind of like to get 1 other species. I like the corys a lot, would I have room for any of them? would they go well in the tank? Just feel like something is missing atm. If more species would be a bad idea, I'll probably follow your original advice and get more odessa barbs.

Thanks a lot, I really appreciate the help.

 

[coldmachineUK]

I'm not sure adding another species in the mix at this point would be a good idea...
If the otos are not being bothered by the barbs, I would get at least one more possibly two - they really do better in groups. Barbs are also proven to be less aggressive fin nippers if there's at least five of them to spread aggression so I'd also up the odessas to a group of 6.

So, you'd have:
6x Odessa Barb
3x Hatchetfish
3-4x Otos
1x Rainbow Shark
1x Snail
1x Frog

I'm still not sure a group of 3 hatchets is a good idea in a 20G personally

 

[DepotFish]

I'd take back the barbs and increase the tetras, barbs can get quite aggressive. Either way, you should end up with two small schools of any of the tetras or barbs you have.
Leave the hatchets.
Get two more otos.
Leave the platies if you really want. They can be aggressive as they grow.
Get rid of the shark, it will get too big and start nipping other fish.
Leave the frog.

The 1" per gallon rule is absolute garbage. But if you insist on using it, you must know that its based on adult size, not current size. And also it is only for normal bodied fish like tetras and livebearers--it should never be used for angels, cichlids, goldfish, sucker fish and other odd fish.

 

[malloc]

Well it's been about 3 weeks since I took back all those fish. My water quality seems to have improved & fish all seem happy & healthy. I now have...

3 Odessa Barbs
3 Marbled Hatchetfish
2 Otocinclus
1 Rainbow Shark
1 African Dwarf Frog
1 Apple Snail

Everyone gets along well, but the tank seems a bit empty. I have a lot of hiding places that some of the fish spend a lot of time in. I would really like to get a few corys. I'm think 3 of a species that stays around 1.5". Any thoughts on this? (I know you already recommend getting more barbs instead of adding a new species =P )

I also wouldn't mind adding 1 more odessa barb, but I'm afraid to overpopulate again (if I get corys as well), and I'd rather have corys =P

Get rid of the shark, it will get too big and start nipping other fish.

I am quite attached to the shark, so decided to keep him. He chases barbs sometimes (ignores everyone else), but *never* nips, fins all look perfect. How fast do these guys grow? He is barely 2.5" now, including a long tail. He has not grown noticeably in the 6 months since I bought him.

Edit: I also plan on upgrading the filter from the whisper20 that came with the tank to an aquaclear. would an aquaclear 30 be good? or is a 20 fine? is there such a thing as too much filtration?

 

[courtnee]

I thought these sharks can get 6"+?

I stand by Serpae Tetras. They are aggressive little things but only to themselves. I had 4 and moved up to 8 where I am now and adore these fish. Their coloring is bright and wonderful. I have white skirts and bleeding heart tetras in with them and they all school together fine. The serpae and bleeding hearts look the same except coloring. The bleeding hearts are a little bigger too. My glass tetra moved right into the school as well.

I had 8 white skirt, 8 serpae and added in only 3 bleeding hearts and 4 glass (1 died leaving me at 3) and they all school together and it has worked out great.

 

[malloc]

I was not a huge fan of the serpae's. They nipped fins too aggressively, and they always had a sort of ratty appearance because of it.

I was also under the impression that my shark would grow to 5" - 6", but have seen little to no growth since I got him. His colors have improved immensely though =)

 

[coldmachineUK]

In a 20G a redfinned shark will be fine. They grow to 6" or so. However, it might be something to be concerned about if he hasn't grown much in 6 months...they do normally grow fairly quickly (not fast like some fish, but moderately). In 6 months I'd have expected at least 1" worth of growth.
What are your nitrate levels? Check those and then post them here and people might be able to give some advice.

Sharks don't nip (redtailed or redfinned); they just persistently chase until fish are so stressed they die. Redfinned aren't nearly as bad as redtailed so keeping him won't be a problem IMO.

That said, one shark is plenty enough fish for the bottom level of a 20G. The cories are playful little things, and I'm not sure how compatible they'd be with a shark - my guess is, 'not'.

3 odessas is not very many: barbs need larger groups to disperse aggression with a recommended minimum of 6. I still think you'd be better off taking the hatchets back (who again need a larger group than 3) and then increasing the school to 6. It will also make your tank look a little busier too.

As for 'busy' vs. 'crowded'. I think it's a mistake to assume that if you can't see fish out and about that there's not enough of them! Fish which can hide are happy fish. Happy fish are healthy fish. Healthy fish means no stress to owner over having to deal with things like whitespot etc.

 

[malloc]

Thank you for the advice, I was really hoping corys would work well =( Does anyone have experience with sharks + corys together?

My nitrate is basically 0, and has been for months. Is there another possibility for his slow growth? He seems very healthy. like I said, very brilliant colors, etc.

 

[courtnee]

if your NitrAte is zero or close to zero with the load of fish you had and even now that is is slimed way down should still be a worry IMHO.

NitrAtes are normal. I have around 20 at all times and I do weekly gravel vac and 50% PWC.

Serpaes will nip badly if kept in small numbers, larger group (my 8 are fine) and tall plants for them to hide they do great. Mine chase each other but the nipping stopped.

 

[supermazz9]

In a 20G a redfinned shark will be fine. They grow to 6" or so.

Wow...that seems like a lot of fish for a little tank like that...I don't know anything about sharks, but I'm going to assume that it does move from time to time?

Geez, I hope someone backs me up on this one...

 

[Wizzard~Of~Ozz]

I don't see a 6" fish being a problem. I usually multiply the fish length by 2, if it exceeds any dimension of the tank then I consider it a concern. (That's why I went with a 120 (4x2x2) for a 14" Red Sailfin Pleco. )

 

[theotheragentm]

For a 6" fish, I would want a 20 gallon long tank. Fish will fit, but I think swimming room is one thing to consider.

 

[hsherman1986]

I have a red tailed shark, and he leaves everyone in my tank alone. He is in with a school of asst. rainbows (some austrailians, a few bosemanis, a goyder river, and a couple turquoise), 2 3" severums, 1 5" firemouth, 3 dojos, 4 cories, and 3 kuhlis. Its a 55g tank, BTW. Everyone is happy, healthy, and the only aggression is between the firemouth and the severums. He is just about 2" now, and growing fast (he was only 1" when I got him almost 2 months ago)

 

[malloc]

but I'm going to assume that it does move from time to time?

Like I said, he's only ~2.5" now, and growing slowly.

hsherman, mine is pretty peaceful as well. He likes to chase my barbs some, but usually it's only when they invade his territory or when there is food in the tank. He likes to chase the barbs away from the food, but rarely eats it himself, he sticks to the algae =P.

 

[kaz]

ill fix all your problems, buy a bigger tank lol j/k

 

[malloc]

ill fix all your problems, buy a bigger tank lol j/k

I would *love* to, but am currently poor & low on space. After I graduate next year & get a real job, a big tank will be at the top of my list =)

I went and picked up an aquaclear 30 filter today, to replace the whisper20 I've been using. Will this work well for the 20g tank, or will I need to turn the flow down? Is there such a thing as too much filtration?