Diagnose What I Did Wrong With New Tank

[GPXtC02]

First tank I've ever had (15G): did a two-week long fish-less cycle with water culture from a established tank then bought a beta and yellow platy.
After about two weeks with the beta and platy, and about a week and a half ago today, I bought an additional five: two dalmation lyre-tail molly's, a blue gourmie, a small rainbow fin shark, and a small platy-looking fish (can't remember name - it's like an inch long, orange, and the hump on it's head gave it the impression of being upside down).

Did a weekly 25% dechlorinated WC before adding those five fish, but since I've been doing a 25% dechlorinated change every other day (I figured there'd be a sharp spike in ammonia by adding five fish at once to such a small tank). The tank has pretty solid waterfall filtration so I don't think lack of oxygen was the problem. I have yet to change the filter. Water has been a little cloudy since I added the new fish. I have yet to gravel-vac.

Over the past 24-48 hours the beta, lyre-tail molly and upside-down fish died. They looked great just hours before.. swimming around and feeding normally, but hours later I keep finding them dead sitting on the bottom of the tank.

What'd I do wrong here? I don't want to lose the remaining fish. I only tested pH the first week or two via free tests at PETCO and I never had to mess with it much so I figured it'd be fine. I also never invested in ammonia strips because I figured all it would take is common sense + regular WC's. Is that to blame? Is the shark killing them? He's pickin' at the corpses. Help?

 

[dipsydoodlenoodle]

You may have over loaded the tank too quickly for the filter to cope with.

 

[Jenste]

a main problem you need to take care of is your shark....it is small now because it is a baby - but it is going to get much too large for your tank....a 4 foot tank is a minimum for that shark! a 15 gallon is no where near large enough for the shark....and once it matures it is going to become quite territorial and will end up killing your smaller fish...

 

[Malt_Vinegar]

Sounds like your tank was not fully cycled, and dumping 5 new fish in overloaded any bacteria that were growing.

Were you taking readings of the key parameters during this time?

What were these readings?

 

[GPXtC02]

i got a reading today, ph and ammonia were normal, nitrates were a little high, which i guess i could attribute to the amount of left over food in the substrate so i gravel vaced 50% of the substrate up. that might do it?

 

[Assaye]

You say you fishless cycled with mature water . . . unfortunately this won't cycle your tank. If there were any bacteria in the water (and there are very few of the right bacteria living in the water), then they would have died without some fish-waste to feed on. Ammonia can be taken care of with water changes . . . but if you have elevated ammonia levels it could take days (or even weeks) of large daily water changes. Unless you know exactly how high the ammonia is and how fast it is building up, you can't know how much water you need to change and how often. A weekly, bi-weekly or even tri-weekly water change will not keep elevated ammonia levels down adequately. The weekly water change is to rebalance minerals, keep pH stable, remove build-up of stuff we don't test for and moderate nitrate levels, not to mention just adding an injection of fresh water.

You also need to be doing gravel vacs at least once every two weeks. Stuff festering in the gravel will destabilise your water quality.

Nitrates are not to be worried about too much, as you said you had a high reading. In theory nitrate can get as high as 80-100 ppm without adversely affecting fish but we tend to try to keep it as low as possible (5-40 is good).

Nitrites are much more of a concern. Like ammonia, nitrites must be zero or they will damage the fish.

Have a read of our beginners' resources to see how your husbandry matches up and take on any changes recommended:

Linky

A word of warning - that shark will rapidly outgrow your tank. He needs about 40 gallons.

Get yourself your own liquid test kit (strips are notoriously bad) and start testing daily for ammonia and nitrites. If they are zero, then stop testing unless you make a change (like adding new fish) or you have a reason to think something isn't right in the tank. A precautionary weekly test is a good idea in the first few months.

Good luck!

 

[GPXtC02]

I still don't get it. I did a gravel vac for the first time three days ago but my other platy died today. I had vac'd about 40% of the substrate, and doing so pretty much resulted in a 40% water change. I still don't get what's goin on! ph and ammonia register at normal

 

[GPXtC02]

bump for dead fish

 

[gbailey141]

Hi there,

sorry to hear about the loss of your fish. Its quite upsetting when you feel like you have done everything you can and they still die. Reading back through the thread I wouldn't be surprised if the damage to them had been done in the early stages with too much ammonia being present in the tank. This is very harmful to fish and some just don't recover. As others have said you need to buy yourself a proper water testing kit, API is quite commonly used on here by other members.Do all the tests in the kit and post your readings on here and there will be plenty of people who can advise.

Good luck.

Gav