Fish Symptoms : My marbled angelfish is constantly lying down flat against the bottom of the tank or against a bed of grass. it also seems to put more effort into swimming when compared to my other angelfish. when i walk past the tank or put food in he rises from the bottom and swims as if nothing is wrong and feeds like normal. there is no loss in appetite but he does lie down all the time, basically whenever he isn't feeding or disturbed by the other fish. my other angel does boss it around a bit but nothing extreme. there is no constant chasing. i did read somehwere that marbled angelfish get exhausted from stress and lie flat for a while but if this is true then he must be constantly stressed!! any suggestions would be great because i'm at a loss and i don't want him to die.
Tank size: 800x300x400 mm. 96 litres / 21 uk gallons
pH:6.4
ammonia: 0
nitrite: 0
nitrate: 50
kH:0 dH
gH: 3 dH
tank temp:78 f 25.5 C
Volume and Frequency of water changes: 10% every 2 weeks
Chemical Additives or Media in your tank: plantfood, green-x phospate remover, water conditioner when water changing, pH up (doesn't work)
Tank inhabitants: 1 other angel, 1 dwarf gourami, 10 cardinal tetras, 2 kuhli loaches
Recent additions to your tank: i did add a pearl gourami but it was a bully plus i was worried about space so i took it back to pet store
Exposure to chemicals: n/a
Digital photo :

Tank size: 800x300x400 mm. 96 litres / 21 uk gallons
pH:6.4
ammonia: 0
nitrite: 0
nitrate: 50
kH:0 dH
gH: 3 dH
tank temp:78 f 25.5 C
Volume and Frequency of water changes: 10% every 2 weeks
Chemical Additives or Media in your tank: plantfood, green-x phospate remover, water conditioner when water changing, pH up (doesn't work)
Tank inhabitants: 1 other angel, 1 dwarf gourami, 10 cardinal tetras, 2 kuhli loaches
Recent additions to your tank: i did add a pearl gourami but it was a bully plus i was worried about space so i took it back to pet store
Exposure to chemicals: n/a
Digital photo :
