new danio on the bottom

[zoezealand]

I filled a new tank earlier, and just added 3 new zebra danios (to start cycling), 2 are fine, but one just stays on the bottom, breathing heavily

tank is 3foot by 1foot,

its on the bottom of a 2 tier stand, away from direct light,

only fish are 3 zebra danios

filtration- sponge, box and internal filter, second hand, but without bacteria

pH = 7.4 ish

heater set to 24 degrees, but hasnt come on, as temp is ~27 (in brisbane)

when i filled it up this morning (6 hours prior to buying fish), i used half new water (dechlorinated) and half from a larger tank above (which has been running for a week, cycling on danios and platties (they are fine))

no ammonia tests, but i changed a bucket of water already, and I dont think ammonia could build up so quickly

other 2 fish fine

I floated the fishes bag in the tank for 20mins, then added water slowly

when he swims it is like is tail is heavy, and it sinks.

feed small amount of frozen bloodworm and flake 1 hours after they had been in tank,

9.5 hours later, I noticed this behaviour

I added small amount of aquarium salt (~1 teaspoon)

turned off air curtain, so he could swim easier

I just checked, and he is swiming more now, but still sinking and staying on bottom

any ideas appreciated

thanks

[zoezealand]

hes up from the bottom now,

but stays at the top, in one corner (near the filter)

he wont move from the spot,

the others are racing round and exploring, but he just stays there,

any advice?

[Caryl]

Perhaps he just got stressed on the way home etc. Hopefully he will perk up soom. It won't be ammonia with just 3 fish and the other 2 are OK.

[zoezealand]

Update:

I think you were right caryl, he seems fine now, i will still keep an eye on him tho

thanks