30 Gallon, Mixed Wrong Fish

[avri2119]

I know now to read about things myself before heading to purchase fish. My daughter and I relied on information from a Petsmart employee to recommend fish to add to our group of 2 cory catfish and 1 dwarf gourami (powder blue). They were calm and happy. 
 
Now, our 30 gallon tank is home to 2 cory catfish, 6 dwarf gouramis (different colors), and 2 buenos aires tetras...
There were 3 tetras, but one didn't last through the night. 
 
I've read nothing but BAD news about keeping 6 dwarf gouramis together. And the buenos aires information says they're to be kept in schools of 6 or more. I don't want anymore of those! They seem to be aggressive. 
 
I can take some back and exchange... but any advice on exactly WHAT to have in the tank would be great. 
Please help!

 

[eaglesaquarium]

Most shoaling species act more aggressive when they are kept in smaller numbers than they prefer.  That's likely the reason the buenos aires tetras are acting out.  
 
Rehome all the dwarf gouramis except one.  Keep the tetras and add more and add more to the cories too.  They need numbers.

 

[avri2119]

If I keep the buenos aires tetras, are there any other fish types that might be a good addition later to the gourami/tetra/cory mix? I was trying to maintain a peaceful community. My research is making me believe they were a poor choice (aggression among the school in larger groups).
Thank you.

 

[eaglesaquarium]

Other options would be other tetra species.  Neons would work.  Bloodfin tetras, lampeye, glowlight, etc. harlequin rasboras, or any of those type (hengeli or espei as well).

Regarding buenos aires (from seriouslyfish):
 
 

Behaviour and Compatibility
Has a reputation for nipping the fins of tankmates though this behaviour only tends to be pronounced when insufficient numbers are purchased or space is limited.
It is a gregarious species forming loose hierarchies, with rival males continually battling with each other for female attention and positioning within the group.
A group of at least 8-10 specimens should be considered the minimum requirement since this increases the likelihood that the fish will be distracted by each other rather than their tankmates but will result in a more effective, natural-looking display. Males will also show better colouration in the presence of conspecific rivals.
That said it is relatively boisterous and doesn not make an ideal companion for very shy, slow-moving, or long-finned fishes such as many livebearers, cichlids, and anabantoids.
Robust fishes inhabiting similar biotopes in nature, especially comparably-sized, open water-dwelling characids perhaps constitute the best choices but other potential options include callichthyid, loricariid and doradid catfishes or benthic anostomids and curimatids from genera such as Schizothorax and Characidium.
If geography is not an issue many rainbowfishes and cyprinids are also suitable, but be sure to research your choices thoroughly before purchase.

 

[avri2119]

Thank you for the information. 

 

[Byron]

I agree with all that JD has posted (though I would caution that Bloodfin Tetras have a tendency to fin nip too, I'll come back to this).  My advice at this point would be for you to return (assuming this is possible) the Buenos Aires tetra, and five of the gourami.  If you can be certain of male/female, keeping a male (only one) and 1-2 females would work.  If you want gourami.
 
The BA tetras, regardless of numbers can still be problems with sedate fish, and gourami are sedate fish.  Active fish frequently disturb sedate fish just by their swimming, but sedate fish frequently serve to entice shoaling fish to nip, even otherwise peaceful species.  A 30g is also small space to this particular tetra.  Bloodfins also have a reputation to nip, all the species in this particular genus (Aphyocharax) do, some species much worse than others.
 
The corys are social fish that live in very large groups, so minimum five or six, more preferable.
 
Byron.