Peaceful Community Tank To Crazy Aggressive Tank?

[rossyboy]

Hi guys having a spot of trouble?

My tanks been established for about 4 months and has been fine from the start with no illness or deaths either.

It's stocked with-

4 Neon tetras
8 harlequins
8 silver tip tetras
1 silver shark
1 dwarf gourami
5 black widows
2 corys
1 yamato shrimp

The tank is approximately 140litres

I've done all tests on water quality with all readings showing as fine, temps at 28 C.

All water put in the aquarium is de-chlorinated too.

Filtration is through a 'built in' jewel filter.


Just over this weekend the fish seem to be going mad, turning into a very aggressive bunch... particularly the silver shark and black widows?

There is only one thing i can think of and i doubt it'd cause this... but i recently added another lighting tube to use after dusk which is a moonlight effect, basically a blue cathode and i turn this one on after 9pm for a few hours.

Any ideas guys, because i'm clueless!?

 

[doubledee]

Hi,

Black Widows can turn into fin nippers but you don't really have any long finned fish for them to annoy. Are they just being agressive within their group or towards other fish? The tank is a little on the small side for a silver shark, so I would look at returning him to the LFS before you get too attached to him. Sharks can be agressive to similar looking species. I use 3 small blue Marina lights for the same effect and haven't noticed any change. Have you tried leaving it off for a few days? I very much doubt it's the blue light, unless it's really bright at night, mine just give the tank a moonlight eery glow. I only really started using it after my apistos spawned again to try and keep an eye on the tank at night.

How is the tank decorated, as sometimes adding plants, rocks and wood to break up sight lines and territories can help to minimise agression?

The temp is a little on the high side too, I would look at turning it down to 24-25 as some species of cories and shrimp do not like high temps like that.

 

[rossyboy]

OK thanks for that, i'll reduce the temp down to 25ish.

Also... the aggression from the black widows is generally towards eachother, but then sometimes it's the shark who chases them round and this is on a daily basis.

Just today though the whole tank seems to be chasing? Including the harlequins, which is unusual.

Any suggestions what would be a good replacement for the shark if i was to return it??

Oh and... the decor:

I have black sand on the bottom, a large piece of driftwood, a loaaaaad of plants which look cool lol and also a cave i've built out of rocks!

 

[Luketendo]

4 Neon tetras - Probably being picked on
8 harlequins - Probably being picked on
8 silver tip tetras - Will stick up for themselves
1 silver shark - Needs 75g, can be aggressive. Needs shoals of 3-6+
1 dwarf gourami - Can be aggressive.
5 black widows - Can be aggressive.
2 corys - Never aggressive.
1 yamato shrimp - Lonely.

 

[doubledee]

If the shoaling fish seem agressive towards eachother, it's usually harmless. It's just their way of establishing a pecking order and letting each other know their place so to speak. My cardinals occasionally give each other a hard time, the rummies just move around in a shoal all the time, which I like. The male pencilfish are always displaying to eachother. It's just fish!

Your stocking levels are proabably max'd out as it is so I might not bother adding anything else if you return the shark. That said, if your tank is well (over) filtered and you keep on top of the water changes, I'm sure you could add something or just add to your shoals. I prefer a tank with a few different types of fish, rather than one of this, one of that. It amazes me sometimes when I visit my LFS and see someone buying about 6 different types of fish and they're adding them all the same day. This is from a well respected LFS as well. I like dwarf cichlids (apistos) and I've somehow managed to resist setting up another tank to house another couple of pairs but time will tell I suppose.

As long as there are no injuries being caused by the agression, it's probably harmless. Just keep an eye on it.

 

[Inchworm]

Hi rossyboy

Corydoras are schooling fish. It would be good if you added a few more of them. What kind do you have?

 

[rossyboy]

hi..

the corys- one's a spotted cory, sort of leopard print and the others a panda cory. (not sure of proper names)

I never even knew they were schooling fish lol

oh and with regards to the shrimp, he's on his own because 2 have dissapeared mysteriously lol

and i'm definately getting rid of the shark!

 

[Inchworm]

Hi rossyboy

I hope to see some of your posts in the Corydoras section soon. These are delightful little fish that will probably surprise you once you get rid of their aggressive tankmate and add a few companions for them. They can be very active and playful.

 

[Luketendo]

hi..

the corys- one's a spotted cory, sort of leopard print and the others a panda cory. (not sure of proper names)

I never even knew they were schooling fish lol

oh and with regards to the shrimp, he's on his own because 2 have dissapeared mysteriously lol

and i'm definately getting rid of the shark!

Shark won't need feeding crustaceans for a while.

 

[doubledee]

Shark won't need feeding crustaceans for a while.

Some of my shrimp disappear for days or weeks at a time but they breed like guppies anyway, so I don't know how many there are now!

 

[Spooky76]

lol - my shrimps disappeared too

Sharks can be a pain, I had to give mine away too which I didnt like doing. They did get a bit tooooo playful with other fish though, and considering their size it turned ugly a few times, so best take him back.