[Assault0137]

Went to petco looking for something to remove phosphates and came home with 2 Golden Wonder killies.
my dad said they would be fine, and that the biggest problem would be the huge angelfish picking on him. after a day, looks like he is being left alone, but when he gets bigger will he pick on other fish?

 

[Byron]

This fish attains 4-5 inches and is a predator. Smaller fish will or may be eaten, but angelfish that are mature would not be "smaller." I've no personal experience so here is some reliable data on this killifish:

Tropical fish - Aplocheilus lineatus - Striped panchax, Lineatus panchax

Byron.

 

[Assault0137]

Thanks Byron. Didn't mean the angelfish when I said other fish, I probably should have said that I have 2 tiger barbs and 2 red minor tetras. Each about 1.5 inches long. The red minor tetras have long, flowing fins like a Betta.
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[Byron]

Thanks Byron. Didn't mean the angelfish when I said other fish, I probably should have said that I have 2 tiger barbs and 2 red minor tetras. Each about 1.5 inches long. The red minor tetras have long, flowing fins like a Betta.
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I don't know the tank size, but there is a good possibility for trouble here. Both Tiger Barb and Serpae Tetra are shoaling fish that must be in a group. And with these two species, they are prone to fin nip, so a larger group is important, no less than 8 of each species.

You can read more in the profiles, click the shaded names.

The trouble is that shoaling fish in small numbers usually become more aggressive. It is due to the stress inflicted on them by not having more of their own around them.

Byron.

 

[Assault0137]

The only aggression I have noticed with those fish is that the tiger barbs chase each other around. I'll watch the Killies and see what they do
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[Byron]

The only aggression I have noticed with those fish is that the tiger barbs chase each other around.
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Give them time... we cannot change the inherent physiology of a fish.;-)

 

[Assault0137]

Lol. Had a red tailed shark for 2 years, never touched anybody. One day, I wake up and he's terrorizing every fish in the tank. Maybe theyre just overly nice as young fish, like kittens, then they attack anything that moves, including humans.
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[Byron]

This happens. But the serious issue with shoaling fish is that it happens because the fish is not in a suitable environment, and the aquarist could have prevented it. As the fish lives and develops day after day, it "expects" certain things. When those are denied, the fish has stress, and the longer this continues the more internal damage it does. And, sadly, it is irreversible.

The fish is frustrated at being alone, or not with the expected group. Shoaling is there for a reason; each species of fish has evolved over thousands of years to function best in a very specific environment. And having others of its own around it is a large part of that. It may be needed for security, or for social interaction, or for a hierarchy.

When this is denied, the fish has no way to deal with this, except by lashing out or becoming seriously withdrawn which does sometimes occur. In both cases, the fish will not be healthy, and it will have a shortened lifespan. It is not right that we force these conditions on any fish. They deserve better from us.

Byron.

 

[MaktheKnife]

Went to petco looking for something to remove phosphates and came home with 2 Golden Wonder killies.
my dad said they would be fine, and that the biggest problem would be the huge angelfish picking on him. after a day, looks like he is being left alone, but when he gets bigger will he pick on other fish?

I have 2 Golden Wonder Killies (Thor and Loki) and I've not had any issues between my Killies and other fish. However, I did initially have an issue between the GWKs. The slightly larger, Thor, would bully the other (Loki) incessantly. Loki looked so miserable that I moved him to my other tank, where he seems much happier.

Everything I've read calls them a "peaceful community fish" and most of what I've read suggests keeping them in pairs or groups of 3. In my experience, they have both thrived as the single GWK in a mixed community. I've never seen either one get aggressive with any of my other fish, regardless of the size or temperament of the other fish. They tend to hang out at the top of the tank by themselves.
The only 'issues' I've had are Thor nipping my arm when I clean the tank, and Loki eating my Platy fry (which is normal; they have big mouths and they will try to eat pretty much anything they can fit into them, including other fish).

I'd suggest providing adequate plant coverage (either floating or tall plants), making sure they get enough food (they eat at the top/surface) and watching for aggression between the two.