Time for new fish?

Hello
It will be two months at the end of August that my tank has been up and running with the fish in it (5 zebra danios and one female beta).
My husband is eggar to get funner, brighter fish for the tank. Thing is that he doesn't want to get rid of the danios. He just wants to add to the tank as is.
The five danios range about 1.5 - 2 inches each and Beta Bertha is about 2.5 - 3 inches so the tank is a little over crowded as is (10g tank).
So this brings me to my two questions:
1) What hard facts can I give him against just going out and buying more fish to add to the tank?
2) I'm willing to get rid of the danios (either to my friend that wants to start another tank or to my father in law that has a tank that he uses to bring his pond fish in in the winter but wants something in there to look at in all the other seasons) but I really want to keep Bertha in there. So what would be a good combination of funner, colourful fish to put in there with Bertha?

She's been great with the danios. She looked annoyed with them at first but now gets right in there and plays crazily with them! Everyone looks healthy and happy, eating good and playing lots.

Thanks for all your help and advice!

Hi there RVT,
a couple issues to come to mind.
Firstly, the 5 danios = 10 inches of fish in themselves.
With the betta in the 10g tank this is alright.
You dont have room for more fish unless you remove the danios,
unfortunately.
What hard facts can you give him about not adding more fish?
Heres some:
In a small tank, water stability is difficult to maintain.
Hence, this is why we limit our stocking so as to avoid complications.
Heavy stocking of small tanks often results in huge ammonia or nitrites spikes,
either of which can wipe out the entire population in your tank.
In a small tank, illness can spread like wildfire - so if one fish gets sick due
to poor water conditions related to overstocking, it will spread rapidly to the
other fish in the tank, again, which could result in the loss of all your fish.
Stunting issues - even though the fish are small, there is a link between the
stunting of fish and high levels of NitrAtes. When you have a lot of fish that
produce a lot of waste, nitrAtes levels can rise rapidly. In amounts over 60ppm,
Nitrates can cause fish to become stunted and even deformed. This can cause
deformation of organs, cancer, shortened life span, and even the rupturing of
internal organs, and kidney/liver failure. This is why one should limit stocking
and do regular water changes. Live plants also help lessen nitrAte levels.
So , hope that gives him something to chew on a bit!

Basically, you would be looking at replacing the danios with
the same number of fish inches as they are, so about 10 inches
to work with.

Some colorful interesting fish that may fit your need:

Neon or Cardinal Tetras
Lemon Tetra
Harlequin Rasboras / Emerald Rasboras / Lambchop Rasboras /
Pygmy Rasboras
White Cloud Mountain Minnows (regular, gold, or meteor minnows)
These are all schooling fish - you could do a group of 6 of any 1
of these.

Beckfords Pencilfish - can be kept in pairs or larger groups.
Endlers Livebearers - can be kept in 1m - 3f groupings or all males, if you
dont want babies - however Bertha will likely eat any young that are born.

German Blue Rams - small cichlids that are highly intelligent,
colorful, and personable. Keep a m/f pair or a single fish.

those are just some ideas off the top of my head.
You could mix and match a little,
like say you wanted to get a single German Ram, you could
add a pair of Pencilfish as well, or maybe a trio of Endlers.