Any "shoaling" species will always display better (more "normal" or intricate behaviours) in larger numbers,
eg rasboras display different/more complex behaviours when kept in a shoal of 18 - 20, than if a small group of 8-10
Seriously Fish is a great place to start when considering various fish species, eg
Sawbwa resplendens
So if you do want to keep these fish, I'd wait until tank is well grown in before adding them, & then add rather more than 4 (even if all males) as this should spread the aggression & lessen the likelihood of particular fish being targeted ... note including these fish may mean too much "activity" for the B brigittae (& the various species which often ship under the same name) which can be quite a timid species
B brigittae - I'd not consider keeping these in less than a group of 25 - 35, they really can be timid, especially in brightly lit planted tanks (if you look about here, you'll find a few threads commenting on their extreme hiding)
Harlequin "type" rasboras - definetly get 18- 20 of these for fantastic shoaling/schooling displays, they'll range everywhere in the tank, then suddenly appear in formation etc
(I had the purple morph & they are stunning with their brilliant orange - gold heads & dark bodies)
Rams - of any color - I'd begin with 6-8 & hope for some compatible "pairs" (note in the wild these fish only pair bond for the spawning/brood care & then will often partner with different fish for the subsequent spawning), often people will remove all except for a single pair, I prefer to keep these fish in a group in a larger tank (90 cm minimum with lots of cover etc)
Most recently I purchased 7 electric blue rams, ended up with 2 females & 4 males, which were great until I managed to introduce some illness into the tank ending up with 1 female & 2 males ... now they are all in separate tanks (they are too pretty to return to the shop & I didn't like the quality of available blue's to increase group #)
Even in a heavily planted 90 cm tank, it's possible to have a single dominant male (or female) decide to take over so it's good to have backup plans with these fish
I'd consider these to be more bottom - mid oriented, though they will travel everywhere
AND they may decide to go shrimp hunting so I'd get shrimp established first
Shrimp - again I'd begin with 10 - 12 minimum of each species/type ... I love the Tigers! they get my vote as best clean up crew (harder to breed in my tanks than the various cherry types)
P ranga - I'd add these after all other fish are established, here, again, depending which species actually appears in dealer tanks, you may get a smaller fish or a rather larger fish (Seriously Fish offers some discussion on this I believe)
eg rasboras display different/more complex behaviours when kept in a shoal of 18 - 20, than if a small group of 8-10
Seriously Fish is a great place to start when considering various fish species, eg
Sawbwa resplendens
aggressive interactions between rival males
Though gregarious by nature it exhibits shoaling rather than schooling behaviour. Males tend to be engaged in a continual battle for dominance, particularly when maintained in small numbers or in the presence of few females.
The best way to minimise this behaviour is to purchase more females than males; a ratio of 4:1 or more being ideal. Unfortunately females can be hard to find on sale because exporters often prefer to ship only the more colourful males.
So if you do want to keep these fish, I'd wait until tank is well grown in before adding them, & then add rather more than 4 (even if all males) as this should spread the aggression & lessen the likelihood of particular fish being targeted ... note including these fish may mean too much "activity" for the B brigittae (& the various species which often ship under the same name) which can be quite a timid species
B brigittae - I'd not consider keeping these in less than a group of 25 - 35, they really can be timid, especially in brightly lit planted tanks (if you look about here, you'll find a few threads commenting on their extreme hiding)
Harlequin "type" rasboras - definetly get 18- 20 of these for fantastic shoaling/schooling displays, they'll range everywhere in the tank, then suddenly appear in formation etc
(I had the purple morph & they are stunning with their brilliant orange - gold heads & dark bodies)
Rams - of any color - I'd begin with 6-8 & hope for some compatible "pairs" (note in the wild these fish only pair bond for the spawning/brood care & then will often partner with different fish for the subsequent spawning), often people will remove all except for a single pair, I prefer to keep these fish in a group in a larger tank (90 cm minimum with lots of cover etc)
Most recently I purchased 7 electric blue rams, ended up with 2 females & 4 males, which were great until I managed to introduce some illness into the tank ending up with 1 female & 2 males ... now they are all in separate tanks (they are too pretty to return to the shop & I didn't like the quality of available blue's to increase group #)
Even in a heavily planted 90 cm tank, it's possible to have a single dominant male (or female) decide to take over so it's good to have backup plans with these fish
I'd consider these to be more bottom - mid oriented, though they will travel everywhere
AND they may decide to go shrimp hunting so I'd get shrimp established first
Shrimp - again I'd begin with 10 - 12 minimum of each species/type ... I love the Tigers! they get my vote as best clean up crew (harder to breed in my tanks than the various cherry types)
P ranga - I'd add these after all other fish are established, here, again, depending which species actually appears in dealer tanks, you may get a smaller fish or a rather larger fish (Seriously Fish offers some discussion on this I believe)