diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index ab7432fc..56e1483c 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -232,7 +232,7 @@ jobs:
         run: harpy qc -x "--low_complexity_filter" --quiet test/fastq
       - name: harpy qc all options
         shell: micromamba-shell {0}
-        run: harpy qc -a -d -c 21,40,3,0 --quiet test/fastq
+        run: harpy qc -a auto -d -c 21,40,3,0 --quiet test/fastq
   deconvolve:
     needs: [changes, pkgbuild]
     if: ${{ needs.changes.outputs.deconvolve == 'true' && needs.pkgbuild.result == 'success' }}
diff --git a/harpy/_validations.py b/harpy/_validations.py
index 5fb039a0..13e10c98 100644
--- a/harpy/_validations.py
+++ b/harpy/_validations.py
@@ -351,7 +351,11 @@ def validate_regions(regioninput, genome):
 def check_fasta(genofile):
     """perform validations on fasta file for extensions and file contents"""
     # validate fasta file contents
-    opener = gzip.open if is_gzip(genofile) else open
+    try:
+        opener = gzip.open if is_gzip(genofile) else open
+    except:
+        print_error("incorrect file format", f"The file must be plain-text or b/gzipped, but failed to be recognized as either. Please check that [blue]{genofile}[/blue] is indeed a fasta file.")
+        sys.exit(1)
     mode = "rt" if is_gzip(genofile) else "r"
     line_num = 0
     seq_id = 0
diff --git a/harpy/qc.py b/harpy/qc.py
index 704feebe..a9da7138 100644
--- a/harpy/qc.py
+++ b/harpy/qc.py
@@ -12,6 +12,7 @@
 from ._cli_types_generic import HPCProfile, IntList, SnakemakeParams
 from ._cli_types_params import FastpParams
 from ._parsers import parse_fastq_inputs
+from ._validations import check_fasta
 
 docstring = {
     "harpy qc": [
@@ -34,7 +35,7 @@
 @click.option('-n', '--min-length', default = 30, show_default = True, type=int, help = 'Discard reads shorter than this length')
 @click.option('-o', '--output-dir', type = click.Path(exists = False), default = "QC", show_default=True,  help = 'Output directory name')
 @click.option('-t', '--threads', default = 4, show_default = True, type = click.IntRange(min = 4, max_open = True), help = 'Number of threads to use')
-@click.option('-a', '--trim-adapters', is_flag = True, default = False, help = 'Detect and trim adapters')
+@click.option('-a', '--trim-adapters', type = str, help = 'Detect and trim adapters')
 @click.option('--conda',  is_flag = True, default = False, help = 'Use conda/mamba instead of a container')
 @click.option('--setup-only',  is_flag = True, hidden = True, show_default = True, default = False, help = 'Setup the workflow and exit')
 @click.option('--hpc',  type = HPCProfile(), help = 'Directory with HPC submission `config.yaml` file')
@@ -49,11 +50,13 @@ def qc(inputs, output_dir, min_length, max_length, trim_adapters, deduplicate, d
     Provide the input fastq files and/or directories at the end of the command
     as individual files/folders, using shell wildcards (e.g. `data/acronotus*.fq`), or both.
     
-    The input reads will be quality trimmed using:
+    The input reads can be quality trimmed using:
     - a sliding window from front to tail
     - poly-G tail removal
-    - `-a` automatically detects and remove adapters
-    - `-d` finds and remove PCR duplicates
+    - `-a` remove adapters
+      - accepts `auto` to automatically detect adapters
+      - accepts a FASTA file of adapters to remove
+    - `-d` finds and removes optical PCR duplicates
     - `-c` resolves barcodes clashing between unrelated sequences
       - off by default, activated with [4 integers](https://github.com/RolandFaure/QuickDeconvolution?tab=readme-ov-file#usage), separated by commas
       - use `21,40,3,0` for QuickDeconvolution defaults (or adjust as needed)
@@ -71,6 +74,14 @@ def qc(inputs, output_dir, min_length, max_length, trim_adapters, deduplicate, d
         command += snakemake
 
     fqlist, sample_count = parse_fastq_inputs(inputs)
+    if trim_adapters:
+        if trim_adapters != "auto":
+            if not os.path.exists(trim_adapters):
+                raise click.BadParameter(f"--trim-adapters was given {trim_adapters}, but that file does not exist. Please check the spelling or verify the location of the file.")
+            if not os.access(trim_adapters, os.R_OK):
+                raise click.BadParameter(f"--trim-adapters was given {trim_adapters}, but that file does not have read permissions. Please modify the persmissions of the file to grant read access.")
+            check_fasta(trim_adapters)
+
     os.makedirs(workflowdir, exist_ok=True)
     fetch_rule(workflowdir, "qc.smk")
     fetch_report(workflowdir, "bx_count.Rmd")
diff --git a/harpy/snakefiles/qc.smk b/harpy/snakefiles/qc.smk
index 8752cfbd..f450656b 100644
--- a/harpy/snakefiles/qc.smk
+++ b/harpy/snakefiles/qc.smk
@@ -19,7 +19,7 @@ envdir       = os.path.join(os.getcwd(), outdir, "workflow", "envs")
 min_len 	 = config["min_len"]
 max_len 	 = config["max_len"]
 extra 	     = config.get("extra", "") 
-trimadapters = config["trim_adapters"]
+trim_adapters = config.get("trim_adapters", None)
 dedup        = config["deduplicate"]
 deconvolve   = config.get("deconvolve", False)
 if deconvolve:
@@ -30,6 +30,10 @@ if deconvolve:
 skip_reports  = config["reports"]["skip"]
 bn_r = r"([_\.][12]|[_\.][FR]|[_\.]R[12](?:\_00[0-9])*)?\.((fastq|fq)(\.gz)?)$"
 samplenames = {re.sub(bn_r, "", os.path.basename(i), flags = re.IGNORECASE) for i in fqlist}
+if trim_adapters:
+    trim_arg = "--detect_adapter_for_pe" if trim_adapters == "auto" else f"--adapter_fasta {trim_adapters}"
+else:
+    trim_arg = "--disable_adapter_trimming"
 
 def get_fq1(wildcards):
     # returns a list of fastq files for read 1 based on *wildcards.sample* e.g.
@@ -56,7 +60,7 @@ if not deconvolve:
         params:
             minlen = f"--length_required {min_len}",
             maxlen = f"--max_len1 {max_len}",
-            trim_adapters = "--detect_adapter_for_pe" if trimadapters else "--disable_adapter_trimming" ,
+            trim_adapters = trim_arg,
             dedup = "-D" if dedup else "",
             extra = extra
         threads:
@@ -81,7 +85,7 @@ else:
         params:
             minlen = f"--length_required {min_len}",
             maxlen = f"--max_len1 {max_len}",
-            trim_adapters = "--detect_adapter_for_pe" if trimadapters else "--disable_adapter_trimming" ,
+            trim_adapters = trim_arg,
             dedup = "-D" if dedup else "",
             extra = extra
         threads:
@@ -177,7 +181,7 @@ rule workflow_summary:
     params:
         minlen = f"--length_required {min_len}",
         maxlen = f"--max_len1 {max_len}",
-        trim_adapters = "--detect_adapter_for_pe" if trimadapters else "--disable_adapter_trimming" ,
+        trim_adapters = trim_arg,
         dedup = "-D" if dedup else "",
         extra = extra
     run: