65L community tank problems

[Priscacara]

Hi, I have a 65L community tank setup thats been running since November last year. Its an Aquaone Aqua Mode 600 model, filtration and lighting is built in, additional airstone and a 150w heater. For the past 3 weeks I've been losing my female guppies at the rate of 1 every 3 days (allowing for a couple of mortalities then a bigger break between deaths) . From reasearch and advice it appeared the females were just weak stock that couldnt survive birth, almost all died in the afternoon following fry drop. I replaced 6 with large robust looking females but alas I now only have 2 of those left so the weakness theory doesnt sound right as they hadnt dropped that I could see. I may have found the culprit though as last nights victim had a couple of fins missing and gouges along the sides, 1 of the sucking catfish (generic name I think as LFS didnt have a proper name for them) kept harrassing and ripping scales off the goldfish I cycled the tank with and I am starting to think it may be responsible for the guppies as they would be slow moving and out of energy after birthing. Just another theory though. I dont plan on getting any more guppies even if the rest die but would be good to know what happened.

Tank paramaters are ph 7.2, hardness 100ppm, 0.1 ammonia, 0 nitrite, 20 ppm nitrate, temp 26C.

Inhabitants :- 8 guppies, 4m/4f, 12 neon tetra, 1 head and tailight tetra + 1 supposed but isnt ( its a tetra just not sure which yet), 6 glass phantom catfish ( only come out at night but look healthy from what I can see), 2 sucking catfish, 2 clown loaches (recently aquired for snail problem), few guppie fry that have survived approx. 5 about 1cm.

Been thinking of removing all the guppies and the glass catfish and getting 2 rams or kribs, not the ideal conditions for either maybe. Tank has a fake wood and plant centrepiece with decent real planting filling the rest, I have seen some nice real wood with plants growing in the shops so would like to replace fake for real.

Any comments and suggestions much appreciated.

[E4G13M4N]

If the catfish were sold as Sucking catfish or Chinese sucking catfish, they are most likely the cause.

Any good aquaria book will class them as agressive and not meant for the communal aquarium, shops that sell them as peacefull fish clearly dont know what they are doing. They may be fine as babies but as they grow will take to any fish at night they can get a hold of, one of the imported fish we could well do with out,bristlenoses do a better job at cleaning up the algae as well.

Can be sold for cold water, but are a tropical fish so all depends on the room temp, as to wether they survive or not.

I would remove them first and see if the problem continues, if it does then we need to know PH, ammonia levels etc

[Priscacara]

Tx for the reply, Tank paramaters are ph 7.2, hardness 100ppm, 0.1 ammonia, 0 nitrite, 20 ppm nitrate, temp 26C, all taken just before I posted to forums. I've also added 2 pics of the tank with an average quality pic of who the offender is.

[E4G13M4N]

The yellow ones although not quite as agressive as the normal ones can still be quite nasty,

I would look at swapping it for ottocinclus catfish or even borneo suckers instead of going with bristlenoses because of the tank size.

[Priscacara]

Tx again for the reply, I'll contact my store and see if they can take the cats and what they have available to replace them.