Hello AQ and members,

I am dynzor, and have come to your forum after a tragedy of epic proportions (for me anyway... I'm rather devastated). Apologies for the long post too, but I should let you all know the history of my tank if I am to be helped?

I am a fish noob and have only recently become interested in tropical fish when I moved into a new place that felt like it needed a fish tank. I couldnt possibly start with something simple like pet rocks, I had to dive right into tropical fish. For the record, I'm really good at cats and dogs.

I acquired a complete tried and tested tank setup from my brother who successfully had tropical fish for years.

I started out with 6 fish about 10 weeks ago:
2 x black mollies, 2 x angelfish and 2 x clown loach.

I have a 3ft tank which does about 70 gallons of water. I have heater, filter, airstone. No living plants, no amphibians.
I clean filter and do pH testing regularly. Water is conditioned before use, stones, plants and tank artifacts rinsed. I do 1/2 tank water change monthly. No over-crowding.

The only thing I am probably terribly guilty for is over-feeding. I gave 1 spirulina disc for loaches, and pinch of tropical flakes for other fish. I split the spirulina disc in half and dropped in different places in tank as one angelfish tended to guard it so the loaches couldnt get it.

They lived quite happily for 2 weeks, then one loach died mysteriously. I figured it was either previously unwell, or it may have been attacked as the one angelfish seemed to be a bully. Loach body appeared pale but not damaged.

The 5 lived happily for another few weeks, when the other loach died mysteriously.
Then another few weeks passed and I thought the others had ganged on the bully angelfish and murdered him and eaten as much of him as possible and hidden the rest of him somewhere... the tank water went pinkish and had small chunks floating around. (Far-fetched, I know, but I'm a fish noob, I don't know what the little dudes are capable of :P)

I cleaned filter a half dozen times over span of few hours, tested water, a wee bit up on alkalinity but nothing major... Filter cleaning returned the water clear but bully angelfish was nowhere to be seen. The other fish were healthy looking, active, feeding and seemed ok.

Next day, the second angelfish was mysteriously dead, no visible damage, other fish were happy... Bully angelfish was discovered stuck in the bridge alive. I had to dislodge him, he had a broken dorsal fin and flapped around on his side for a couple of days on surface of water, drifted upside down, etc... and then figured out how to swim upright again. Dispite his injury, he and other fish survived a 1/2 water change.

To this day he's a little wonky, but healthy and humbled - he hasnt been a bully since...

After the second angelfish and the 2 loaches were dead, the two mollies bred and had a single baby about three weeks ago. As my mollies seemed happy enough to be breeding, and wonky angelfish was ok I figured all was well in the tank. I thought the Mollies may have been responsible for the unexplained deaths as a precursor for nesting?

2 weeks ago i noticed a 6-7mm long caterpillar-looking organism climbing up the bridge. It got washed amongst the stones by the flow from the filter and I havent seen it since. There was only one that I saw. I read some stuff about tank worms afterwards and it didnt seem to fit any description, but as some tank worms were not harmful I didnt worry about it.

Baby fish is happy, and mummy and daddy fish seemed ok, tho mummy fish seemed sick of daddy fish from time to time, where before she had baby fish they couldn't get enough of each other (I see some things don't change even for fishes :P).

2 days ago, I noticed a thin, bright green algae or slime-like growth on the underside of the tank lid. It was not in direct contact with the water. I took the lid off and washed it.

I also noticed pale grey flecks on my mummy fish on one side of her body. They weren't distinct spots as what I gather "white spot" to be, it resembled small rings and flecks like waterstains when water has dripped on paper or fabric and then dried.

Also daddy fish has been resting on the floor of the tank for a few days now, I thought he was dead thismorning but he is still alive, just not as active. Baby fish and wonky angelfish are still active and eating.

I've been expecting mummy fish to drop more fry in the next week or so. She was very heavy looking, though she was eating and was quite mobile, however, she was alive this morning, and when I got home from work, she was dead.

I was very upset about this as myself and the kids were looking forward to maybe catching her have babies, and it was a surprise because I thought if anyone was gonna go, it would have been daddy fish cuz he had the suspicious lethargic behaviour...

I checked her body, none of the fry inside were alive. I was really bummed out and so decided to come to you guys to see if I have infact done something wrong to cause this, or whether spontaneous deaths are normal, or if there is a nasty in my tank that I need to treat...

I don't want my fish interests to be thwarted in only 3 months... I would like to keep my remaining fish alive and successfully introduce a couple more into the tank to replace the ones I've lost, but I don't want to do so unless I'm doing things right and they stand a chance!

I have so many questions like:
Why my mummy fish? :'(
What was the green algae and how did it get there?
What was the caterpillar thingo?
Whats the go with the grey flecks?
Is there something I should be doing?
Why do I never have high acidity, only raised alkalinity issues?
Are my fish diseased and I don't know it?
So on, and so forth...

Any advice and support would be appreciated...
Thanks in advance!